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Nε -lysine acetylation is recognized as a prevalent post-translational modification (PTM) that regulates proteins across all three domains of life. In Bacillus subtilis, the histone-like protein HBsu is acetylated at seven sites, which regulates DNA compaction and the process of sporulation. In Mycobacteria, DNA compaction is a survival strategy in response antibiotic exposure. Acetylation of the HBsu ortholog HupB decondenses the chromosome to escape this drug-induced, non-growing state, and in addition, regulates the formation of drug-tolerant subpopulations by altering gene expression. We hypothesized that the acetylation of HBsu plays similar regulatory roles. First, we measured nucleoid area by fluorescence microscopy and in agreement, we found that wild-type cells compacted their nucleoids upon kanamycin exposure, but not exposure to tetracycline. We analyzed a collection of HBsu mutants that contain lysine substitutions that mimic the acetylated (glutamine) or unacetylated (arginine) forms of the protein. Our findings indicate that some level of acetylation is required at K3 for a proper response and K75 must be deacetylated. Next, we performed time-kill assays of wild-type and mutant strains in the presence of different antibiotics and found that interfering with HBsu acetylation led to faster killing rates. Finally, we examined the persistent subpopulation and found that altering the acetylation status of HBsu led to an increase in persister cell formation. In addition, we found that most of the deacetylation-mimic mutants, which have compacted nucleoids, were delayed in resuming growth following removal of the antibiotic, suggesting that acetylation is required to escape the persistent state. Together, this data adds an additional regulatory role for HBsu acetylation and further supports the existence of a histone-like code in bacteria. [ABSTRACT FROM AUTHOR]

Nε-lysine acetylation is recognized as a prevalent post-translational modification (PTM) that regulates proteins across all three domains of life. In Bacillus subtilis, the histone-like protein HBsu is acetylated at seven sites, which regulates DNA compaction and the process of sporulation. In Mycobacteria, DNA compaction is a survival strategy in response antibiotic exposure. Acetylation of the HBsu ortholog HupB decondenses the chromosome to escape this drug-induced, non-growing state, and in addition, regulates the formation of drug-tolerant subpopulations by altering gene expression. We hypothesized that the acetylation of HBsu plays similar regulatory roles. First, we measured nucleoid area by fluorescence microscopy and in agreement, we found that wild-type cells compacted their nucleoids upon kanamycin exposure, but not exposure to tetracycline. We analyzed a collection of HBsu mutants that contain lysine substitutions that mimic the acetylated (glutamine) or unacetylated (arginine) forms of the protein. Our findings indicate that some level of acetylation is required at K3 for a proper response and K75 must be deacetylated. Next, we performed time-kill assays of wild-type and mutant strains in the presence of different antibiotics and found that interfering with HBsu acetylation led to faster killing rates. Finally, we examined the persistent subpopulation and found that altering the acetylation status of HBsu led to an increase in persister cell formation. In addition, we found that most of the deacetylation-mimic mutants, which have compacted nucleoids, were delayed in resuming growth following removal of the antibiotic, suggesting that acetylation is required to escape the persistent state. Together, this data adds an additional regulatory role for HBsu acetylation and further supports the existence of a histone-like code in bacteria.

Background: Cholinesterase is a biomarker for poisonings by anticholinesterase agents, but its reference values are scarce, and possible interaction with collars containing parasiticides has not been studied. Objectives: We aimed to evaluate the serum cholinesterase activity of healthy dogs without a history of contact with anticholinesterase agents and healthy animals exposed to commercial collars containing organophosphate. Methods: Ninety‐nine dogs were used and included healthy animals without recent exposure to anticholinesterase agents and healthy animals previously exposed to diazinon collars. Serum quantification of the enzyme butyrylcholinesterase (BuchE) through spectrophotometry was conducted on all samples. In experiment 1, BuchE activity was quantified at time 0 and 7 days after, a time when the samples were kept at −18°C. In experiment 2, sampling times were 0, 7, 14, 21, 28, and 56 days. Results: Time 0 values were 4622.38 ± 1311.53 U/L. After 7 days, a significant decay was observed, with a mean of 3934.45 ± 1430.45 U/L. Spearman's test was performed, finding a weak correlation between ALT, creatinine, total plasma proteins, age, weight, red blood cells, platelets, leukocytes, and BuchE activities. In experiment 2, the mean at time 0 was 4753 ± 454.8 U/L. With exposure to the collar, there was a decay of up to 93% after 14 days. Conclusions: Normality values of serum BuchE in healthy dogs without a history of exposure to anticholinesterase agents were 4360.8–4883.96 U/L. Freezing serum caused a decrease in BuchE activity. Exposure to commercial collars containing diazinon also reduced BuchE activity without clinical signs, indicating that previously exposed animals should be evaluated carefully. [ABSTRACT FROM AUTHOR]

The production of biofuels and biochemicals requires a pretreatment to cleave the composite-like structure of lignocellulosic biomass and thus facilitate further conversion. In the case of liquid-based pretreatment, it is important to know which pretreatment liquids allow for an effective conversion of biomass. For the development of effective pretreatment strategies, simple criteria for a fast evaluation of pretreatment results are advantageous. In this study, we use the example of acetosolv pretreatment of beech wood to explore the influence of composition of the employed acetosolv liquids. To this end, we investigate pretreatment phenomena on different scales including macroscopic disintegration, overall mass balances and compositional changes of beech wood. We relate the investigated phenomena with the type and amount of catalyst acid as well as water content of the employed acetosolv liquids. The results show that disintegration increases with both a higher concentration and acidity of the catalyst acid, while excessive disintegration can be balanced by an increased water content up to equimolar ratios of water and acetic acid. Furthermore, an increasing disintegration correlates with an increasing non-recovered fraction up to a maximum of 40 wt%. The non-recovered fraction in turn linearly depends on the amount of removed hemicellulose and lignin. Overall, a low lignin content together with complete disintegration after pretreatment in acetosolv liquids with a high water content allows for increased sugar yields in subsequent enzymatic hydrolysis. Thus, disintegration and non-recovered fraction serve as a simple indicator for a first assessment of pretreatment effectiveness. [ABSTRACT FROM AUTHOR]

The constitutional challenge of an electrostatically directed meta borylation of sterically biased and unbiased substrates is summarized in the present work. The borylation follows an electrostatic interaction between the partially positive and negative charges of the ligand and substrate, respectively. Using our developed strategy, it has been demonstrated that a wide range of challenging substrates, especially 4-substituted substrates can be borylated at the meta position with excellent selectivity. Moreover, unsubstituted substrates are also displayed excellent meta selectivity. The reaction employs bench-stable ligand, proceeds at moderate reaction temperature (40–80 °C), precluding the need to synthesize bulky and sophisticated ligand/template. [ABSTRACT FROM AUTHOR]

The title compounds, [Mo(C5H5)(COCH3)(C6H12N3P)(CO)2], (1), and [Mo(C5H5)(COCH3)(C9H16N3O2P)(C6H5)2))(CO)2], (2), have been prepared by phosphine-induced migratory insertion from [Mo(C5H5)(CO)3(CH3)]. The molecular structures of these complexes are quite similar, exhibiting a four-legged piano-stool geometry with trans-disposed carbonyl ligands. The extended structures of complexes (1) and (2) differ substantially. For complex (1), the molybdenum acetyl unit plays a dominant role in the organization of the extended structure, joining the molecules into centrosymmetrical dimers through C—H...O interactions with a cyclopentadienyl ligand of a neighboring molecule, and these dimers are linked into layers parallel to (100) by C—H...O interactions between the molybdenum acetyl and the cyclopentadienyl ligand of another neighbor. The extended structure of (2) is dominated by C—H...O interactions involving the carbonyl groups of the acetamide groups of the DAPTA ligand, which join the molecules into centrosymmetrical dimers and link them into chains along [010]. Additional C—H...O interactions between the molybdenum acetyl oxygen atom and an acetamide methyl group join the chains into layers parallel to (101).

Timber is one of the most common historic building materials, but relatively little is known about how it ages in situ. Here we investigate historic and modern Scots pine to determine any chemical or mechanical differences between them. Fourier-transform infrared (FTIR) microscopy was used to investigate differences in the chemical composition of Scots pine (Pinus sylvestris L.) timber, comparing small samples from historic beams about 500 years old with modern timber. The hemicellulosic acetyl content was reduced by about half in the historic samples, uniformly across the thickness of the beams. A chemical mechanism was therefore suggested for the loss of acetyl groups, as has been observed in paper. In paper, deacetylation and the resulting release of acetic acid are accompanied by loss of strength. Mechanical testing of the historic timber was difficult because the available length of the samples along the grain was only 20 mm. After developing a miniaturized compression test developed for the purpose, it was shown that the relative stiffness of the historic Scots pine samples was reduced by about half compared to modern material.

Pb-related imperfections (surface or halide vacancy induced uncoordinated Pb 2+ , Pb-I antisite, and Pb 2+ vacancy defects) of the ionic crystal perovskite film seriously restrict the photovoltaic performance of perovskite solar cells (PSCs). Here, an aniline derivative N-(4-cyanophenyl)acetamide (CAL) is rationally designed, incorporating bilateral functional sites of cyano and acetyl groups, acting as Lewis base molecule for managing the Pb-related imperfections in perovskite surface through post-treatment. Theoretical calculation and experimental verification together proved the reduced defect density, improved crystallinity, and inhibited ion migration in the CAL-modified perovskite. Precisely, cyano as a side group and acetyl as another side group can both coordinate with Pb 2+ for its low electrostatic potential energy. Further, the aniline core and the π-π conjugate structure in the benzene ring of the ligand tend to form a dimer to improve the mobility for carrier transportation and collection. The strategy demonstrates a champion PCE of 24.35% for the air-processed PSCs with over 1200 hours of maximum power point tracking (MPPT) stability. This study presents a comprehensive approach to overcoming the current Pb-related imperfections induced limitations in PSCs, paving the way for their integration into mainstream solar technologies., (© 2024 Wiley‐VCH GmbH.)

Post-translational modifications (PTMs) have been extensively studied in both eukaryotes and prokaryotes. Lysine acetylation, originally thought to be a rare occurrence in bacteria, is now recognized as a prevalent and important PTM in more than 50 species. This expansion in interest in bacterial PTMs became possible with the advancement of mass spectrometry technology and improved reagents such as acyl-modification specific antibodies. In this Review, we discuss how mass spectrometry-based proteomic studies of lysine acetylation and other acyl modifications have contributed to our understanding of bacterial physiology, focusing on recently published studies from 2018 to 2023. We begin with a discussion of approaches used to study bacterial PTMs. Next, we discuss newly characterized acylomes, including acetylomes, succinylomes, and malonylomes, in different bacterial species. In addition, we examine proteomic contributions to our understanding of bacterial virulence and biofilm formation. Finally, we discuss the contributions of mass spectrometry to our understanding of the mechanisms of acetylation, both enzymatic and nonenzymatic. We end with a discussion of the current state of the field and possible future research avenues to explore.

Bacillus subtilis produces dormant, highly resistant endospores in response to extreme environmental stresses or starvation. These spores are capable of persisting in harsh environments for many years, even decades, without essential nutrients. Part of the reason that these spores can survive such extreme conditions is because their chromosomal DNA is well protected from environmental insults. The α/β-type small acid-soluble proteins (SASPs) coat the spore chromosome, which leads to condensation and protection from such insults. The histone-like protein HBsu has been implicated in the packaging of the spore chromosome and is believed to be important in modulating SASP-mediated alterations to the DNA, including supercoiling and stiffness. Previously, we demonstrated that HBsu is acetylated at seven lysine residues, and one physiological function of acetylation is to regulate chromosomal compaction. Here, we investigate if the process of sporulation or the resistance properties of mature spores are influenced by the acetylation state of HBsu. Using our collection of point mutations that mimic the acetylated and unacetylated forms of HBsu, we first determined if acetylation affects the process of sporulation, by determining the overall sporulation frequencies. We found that specific mutations led to decreases in sporulation frequency, suggesting that acetylation of HBsu at some sites, but not all, is required to regulate the process of sporulation. Next, we determined if the spores produced from the mutant strains were more susceptible to heat, ultraviolet (UV) radiation and formaldehyde exposure. We again found that altering acetylation at specific sites led to less resistance to these stresses, suggesting that proper HBsu acetylation is important for chromosomal packaging and protection in the mature spore. Interestingly, the specific acetylation patterns were different for the sporulation process and resistance properties of spores, which is consistent with the notion that a histone-like code exists in bacteria. We propose that specific acetylation patterns of HBsu are required to ensure proper chromosomal arrangement, packaging, and protection during the process of sporulation.

Bacillus subtilis produces dormant, highly resistant endospores in response to extreme environmental stresses or starvation. These spores are capable of persisting in harsh environments for many years, even decades, without essential nutrients. Part of the reason that these spores can survive such extreme conditions is because their chromosomal DNA is well protected from environmental insults. The α/β-type small acid-soluble proteins (SASPs) coat the spore chromosome, which leads to condensation and protection from such insults. The histone-like protein HBsu has been implicated in the packaging of the spore chromosome and is believed to be important in modulating SASP-mediated alterations to the DNA, including supercoiling and stiffness. Previously, we demonstrated that HBsu is acetylated at seven lysine residues, and one physiological function of acetylation is to regulate chromosomal compaction. Here, we investigate if the process of sporulation or the resistance properties of mature spores are influenced by the acetylation state of HBsu. Using our collection of point mutations that mimic the acetylated and unacetylated forms of HBsu, we first determined if acetylation affects the process of sporulation, by determining the overall sporulation frequencies. We found that specific mutations led to decreases in sporulation frequency, suggesting that acetylation of HBsu at some sites, but not all, is required to regulate the process of sporulation. Next, we determined if the spores produced from the mutant strains were more susceptible to heat, ultraviolet (UV) radiation and formaldehyde exposure. We again found that altering acetylation at specific sites led to less resistance to these stresses, suggesting that proper HBsu acetylation is important for chromosomal packaging and protection in the mature spore. Interestingly, the specific acetylation patterns were different for the sporulation process and resistance properties of spores, which is consistent with the notion that a histone-like code exists in bacteria. We propose that specific acetylation patterns of HBsu are required to ensure proper chromosomal arrangement, packaging, and protection during the process of sporulation. [ABSTRACT FROM AUTHOR]

Fast-growing broad-leaf tree species can serve as feedstocks for production of bio-based chemicals and fuels through biochemical conversion of wood to monosaccharides. This conversion is hampered by the xylan acetylation pattern. To reduce xylan acetylation in the wood, the Hypocrea jecorina acetyl xylan esterase (HjAXE) from carbohydrate esterase (CE) family 5 was expressed in hybrid aspen under the control of the wood-specific PtGT43B promoter and targeted to the secretory pathway. The enzyme was predicted to deacetylate polymeric xylan in the vicinity of cellulose due to the presence of a cellulose-binding module. Cell-wall-bound protein fractions from developing wood of transgenic plants were capable of releasing acetyl from finely ground wood powder, indicative of active AXE present in cell walls of these plants, whereas no such activity was detected in wild-type plants. The transgenic lines grew in height and diameter as well as wild-type trees, whereas their internodes were slightly shorter, indicating higher leaf production. The average acetyl content in the wood of these lines was reduced by 13%, mainly due to reductions in di-acetylated xylose units, and in C-2 and C-3 mono-acetylated xylose units. Analysis of soluble cell wall polysaccharides revealed a 4% reduction in the fraction of xylose units and an 18% increase in the fraction of glucose units, whereas the contents of cellulose and lignin were not affected. Enzymatic saccharification of wood from transgenic plants resulted in 27% higher glucose yield than for wild-type plants. Brunauer–Emmett–Teller (BET) analysis and Simons’ staining pointed toward larger surface area and improved cellulose accessibility for wood from transgenic plants compared to wood from wild-type plants, which could be achieved by HjAXE deacetylating xylan bound to cellulose. The results show that CE5 family can serve as a source of enzymes for in planta reduction of recalcitrance to saccharification.

Lignocellulose is a resource for renewable organic matter. Between the three main components, hemicellulose is the second most abundant natural polymer on earth, its main constituent being xylan. Acetyl xylan esterases are accessory enzymes involved in biodegradation of xylan, releasing acetic acid from side chains of xylan backbone. After the action of these enzymes, other lignocellulases are able to act on their specific substrate. The main microbial sources for acetyl xylan esterase include Penicillium sp., Thermoanarobacterium sp., Aspergillus sp., Fusarium sp., Streptomyces sp., Phanerochaete sp., Bacillus sp., Trichoderma sp. etc. Screening methods for identification of acetyl xylan esterase microorganisms requires specific substrate for this enzyme such as acetylated xylan or xylooligosaccharides, α and β-naphthyl acetate or p-nitrophenyl acetate. The importance of these enzymes is given by their role in various applications such as biofuel production, pulp and paper biobleaching or food and feed. [ABSTRACT FROM AUTHOR]

Fast-growing broad-leaf tree species can serve as feedstocks for production of bio-based chemicals and fuels through biochemical conversion of wood to monosaccharides. This conversion is hampered by the xylan acetylation pattern. To reduce xylan acetylation in the wood, the Hypocrea jecorina acetyl xylan esterase (Hj AXE) from carbohydrate esterase (CE) family 5 was expressed in hybrid aspen under the control of the wood-specific Pt GT43B promoter and targeted to the secretory pathway. The enzyme was predicted to deacetylate polymeric xylan in the vicinity of cellulose due to the presence of a cellulose-binding module. Cell-wall-bound protein fractions from developing wood of transgenic plants were capable of releasing acetyl from finely ground wood powder, indicative of active AXE present in cell walls of these plants, whereas no such activity was detected in wild-type plants. The transgenic lines grew in height and diameter as well as wild-type trees, whereas their internodes were slightly shorter, indicating higher leaf production. The average acetyl content in the wood of these lines was reduced by 13%, mainly due to reductions in di-acetylated xylose units, and in C-2 and C-3 mono-acetylated xylose units. Analysis of soluble cell wall polysaccharides revealed a 4% reduction in the fraction of xylose units and an 18% increase in the fraction of glucose units, whereas the contents of cellulose and lignin were not affected. Enzymatic saccharification of wood from transgenic plants resulted in 27% higher glucose yield than for wild-type plants. Brunauer–Emmett–Teller (BET) analysis and Simons' staining pointed toward larger surface area and improved cellulose accessibility for wood from transgenic plants compared to wood from wild-type plants, which could be achieved by Hj AXE deacetylating xylan bound to cellulose. The results show that CE5 family can serve as a source of enzymes for in planta reduction of recalcitrance to saccharification. [ABSTRACT FROM AUTHOR]

The title compounds, [Mo(C5H5)(COCH3)(C6H12N3 P)(CO)2 ], (1), and [Mo(C5H5)(COCH3)(C9H16N3O2P)(C6H5)2))(CO)2], (2), have been prepared by phosphine-induced migratory insertion from [Mo(C5H5)(CO)3 (CH3)]. The molecular structures of these complexes are quite similar, exhibiting a fourlegged piano-stool geometry with trans-disposed carbonyl ligands. The extended structures of complexes (1) and (2) differ substantially. For complex (1), the molybdenum acetyl unit plays a dominant role in the organization of the extended structure, joining the molecules into centrosymmetrical dimers through C--H…O interactions with a cyclopentadienyl ligand of a neighboring molecule, and these dimers are linked into layers parallel to (100) by C--H…O interactions between the molybdenum acetyl and the cyclopentadienyl ligand of another neighbor. The extended structure of (2) is dominated by C--H…O interactions involving the carbonyl groups of the acetamide groups of the DAPTA ligand, which join the molecules into centrosymmetrical dimers and link them into chains along [010]. Additional C--H…O interactions between the molybdenum acetyl oxygen atom and an acetamide methyl group join the chains into layers parallel to (101). [ABSTRACT FROM AUTHOR]

The aim of the study was to assess the dietary intake of caramel colours and their by-products 4-methylimidazole (4-MEI) and 2-acetyl-4-tetrahydroxybutylimidazole (THI) for the Chinese population. Based on the typical and maximum reported use levels of caramel colours in 15 food categories, the dietary intakes of combined and single-class caramel colours of Classes I, III and IV were estimated with the food consumption data from the China National Nutrient and Health Survey. Using the mean values of 4-MEI and THI contents in Class III and Class IV Caramel colour samples, the exposures to 4-MEI and THI from dietary caramel colours were derived. The results showed that the combined and individual average dietary caramel colour intakes for the Chinese population of different age groups were estimated to be 232–60.3 mg kg−1 bw day−1 for combined caramels, 5.9–29.2 mg kg−1 bw day−1 for Class I, 7.7–29.6 mg kg−1 bw day−1 for Class III, 21.2–54.3 mg kg−1 bw day−1 for Class IV, which were far below the group acceptable daily intake (ADI) and respective ADIs. The combined intake of 4-MEI from Class III and IV caramel colours was estimated to be 3.8–5.2 μg kg−1 bw day−1 on average, and 12.9–27.1 μg kg−1 bw day−1 at 95th-97.5th percentile for the general population. The anticipated exposure to THI from Class III caramel colours was estimated to be 0.1–0.3 μg kg−1 bw day−1 on average and 0.5–1.7 μg kg−1 bw day−1 at 95th–97.5th percentile for the general population. The dietary caramel colours intakes and the exposures to 4-MEI and THI from dietary caramel colour for the Chinese population were considered to be of low health concern based on the present toxicological data. Soy sauce, vinegar and compound seasonings were found to be the main contributors to the dietary intake of caramel colours. [ABSTRACT FROM AUTHOR]

Abstract: A simple and reliable LC–MS/MS method was established for simultaneous determination of 12 components from acetylkitasamycin and kitasamycin in swine plasma. The analytes were separated on a Shim‐pack VP‐ODS column with a 25 min gradient elution using 5 mmol/L ammonium acetate and acetonitrile as the mobile phase at a flow rate of 0.2 mL/min. Identification and quantification were accomplished by electrospray ionization) in positive mode using multiple reaction monitoring. The limits of quantitation of acetylkitasamycin A1A3, A13 and kitasamycin A3, A13 were 3 μg/L, and that of the other eight components was 5 μg/L. The mean recoveries of kitasamycin and acetylkitasamycin ranged from 85.3 to 103.5%. The developed method was successfully applied to a pharmacokinetic study in swine after intravenous (i.v.) and oral (p.o.) administration of acetylkitasamycin. The result showed that the plasma concentrations of acetylkitsamycin components were much higher than that of kitasamycin in swine after i.v. and p.o., in which acetylkitsamycin A4A5 was the highest component at each time point. [ABSTRACT FROM AUTHOR]

Triphenylamine derived bis- and tris-branched donor-pi-acceptor coumarins with acetyl and benzothiazolyl acceptors are studied for their linear and nonlinear optical properties that originate from their photophysical and molecular structure. Plots of solvent polarities versus the Stokes shift, frontier molecular orbital analysis and Generalised Mulliken Hush analysis have established their strong charge transfer character supported by the strong emission solvatochromism of these chromophores. On the basis of excited state intramolecular charge transfer, the first-, second- and third-order polarizability of these dyes are determined by a solvatochromic method and supported by density functional theory calculations using CAM-B3LYP/6-31g(d). Compared to the acetyl group, the benzothiazolyl group is a strong acceptor, and its corresponding derivatives show enhanced absorption, emission maxima and non-linear optical response. Bond length alternation and bond order alternation analysis reveals that these chromophores approach the cyanine-like framework which is responsible for maximum perturbation to produce high nonlinear optical response. Third order nonlinear susceptibility for dyes 1 and 2 is determined by Z-scan measurement. All of these methods are used to determine the nonlinear optical properties, and thermogravimetric analysis suggests that these chromophores are thermally robust and efficient nonlinear optical materials. [ABSTRACT FROM AUTHOR]

The 4-dihydropyrimidin-2(1H)-one moiety of the title molecule, C16H16N2O2, displays a half-chair conformation. The least-squares mean plane through this heterocycle is almost perpendicular to the aromatic ring [dihedral angle = 89.52 (8)°] and to the prop-2-ynyl chain [C—C—N—C torsion angle of −73.2 (2)°]. The mean plane through the acetyl group makes a dihedral angle of 30.93 (10)° with the mean plane of the heterocycle. There is an intramolecular C—H...O hydrogen bond forming an S(6) ring motif. In the crystal, molecules are linked by pairs of N—H...O hydrogen bonds forming inversion dimers.

The title compounds, [Mo(C5H5)(COCH3)P(CH3)2(C6H5)(CO)2], (1), and [Mo(C5H5)(COCH3)P(C2H5)(C6H5)2)(CO)2], (2), have been prepared by phosphine-induced migratory insertion from [Mo(C5H5)(CO)3(CH3)]. Both complex molecules exhibit a four-legged piano-stool geometry with trans-disposed carbonyl ligands along with Mo—P bond lengths and C—Mo—P angles that reflect the relative steric pressure of the respective phosphine ligand. The structure of compound (1) exhibits a layered arrangement parallel to (100). Within the layers molecules are linked into chains along [001] by non-classical C—H...O interactions between the acetyl ligand of one molecule and the phenyl and methyl phosphine substituents of another. In the structure of complex (2), a chain motif of centrosymmetrical dimers is found along [010] through C—H...O interactions.

Hemicellulose is a major component of the lignocellulosic biomass, located between lignin and cellulose fibers and is the second most abundant natural polymer on earth. The main constituent of hemicellulose is xylan, a polysaccharide comprised of β-1.4-linked xylopyranosyl residues. Due to its complex structure and heterogeneous nature, hydrolysis of xylan requires a synergic action of several enzymes generally named xylanases. Amongst them, acetyl xylan esterase (AXE) is an accessory enzyme that liberates acetyl groups from the side chains of the xylan backbone. These acetyl side-groups protect the backbone of xylan from the action of others enzymes, therefore their release facilitates the action of endoxylanases. Several microorganisms display acetyl xylan esterase activity, the main producers being fungi and bacteria. The aim of this study was to test different strains in regard to their ability to display acetyl xylan esterase activity. The microorganisms subjected to screening belonged to the genres: Aspergillus, Penicillium, Bacillus, Trichoderma and Fusarium. The strains subjected for screening were also studied for their xylanase activity, in order to compare their ability to produce both xylanase and acetyl xylan esterase. In addition, the microorganisms selected after the screening process were subjected to protein assay, in order to determine the specific enzymatic activities. The best acetyl xylan esterase activities were detected with Aspergillus brasiliensis ATCC 16404 UV 7, Aspergillus brasiliensis ATCC 16404 UV 5, Aspergillus niger UV 10 and Penicillium digitatum UV 11. These experimental results are significant for further studies related to hydrolysis of hemicellulose, regarding lignocellulosic biomass valorisation. [ABSTRACT FROM AUTHOR]

The reaction of Ru 5 (μ 5 -C)(CO) 15 , 1 with MeAu(PPh 3 ) yielded two major products: Ru 5 (μ 5 -C)(CO) 14 (μ-η 2 -O=CMe)[μ-Au(PPh 3 )], 5 (30% yield) and Ru 5 (μ 5 -C)(CO) 13 (μ-η 2 -O=CMe)(Me)[μ-Au 2 (PPh 3 ) 2 ], 6 (31% yield) and one minor product Ru 5 (μ 5 -C)(CO) 14 (μ-η 2 -O=CMe)(η 1 -O=CMe)[μ-Au 2 (PPh 3 ) 2 ], 7 (2% yield). Compound 6 was also obtained independently in 39% yield by the addition of MeAu(PPh 3 ) to 5 . Compound 7 was also obtained independently in 63% yield by the addition of CO to 6 . The PPh 3 derivative of 5 , Ru 5 (μ 5 -C)(CO) 13 (PPh 3 )(μ-η 2 -O=CMe)[μ-Au(PPh 3 )], 8 was obtained in 76% yield by the reaction of 5 with PPh 3 . Compound 6 eliminates acetone when heated to yield the digold complex Ru 5 (μ 5 -C)(CO) 11 (μ-CO) 2 [μ-Au(PPh 3 )] 2 , 9 . Compound 9 reacts with MeAu(PPh 3 ) to yield the tetragold compound Ru 5 (μ 5 -C)(CO)11(μ-CO) 2 [μ-Au(PPh 3 )] 4 10 . All products have been characterized by single crystal X-ray diffraction analyses. Compounds 5 and 6 contain a bridging acetyl ligand formed by the combination of the methyl group with a CO ligand in opened Ru 5 clusters. Compound 7 contains both a bridging acetyl ligand and a terminally-coordinated acetyl ligand. [ABSTRACT FROM AUTHOR]

The acetyl capping reaction used throughout solid phase oligonucleotide synthesis is meant to minimize n−1 deletionmer impurities by terminating sequences that fail to couple to a phosphoramidite. However, the reaction is also responsible for the formation of a number of impurities. One capping-related impurity has an additional mass of 98 amu from the parent oligonucleotide. The n+98 amu impurity was found to result from modification of an adenine nucleobase. The structure of the impurity was determined by preparation of an oligonucleotide enriched in n+98 amu , enzymatic digestion to individual nucleosides, isolation of the pure nucleoside+98 amu species, crystallization, and X-ray crystallographic analysis. The n+98 amu impurity is an oligonucleotide in which one adenine residue has been converted to 5-amino-4-pyrimidinylimidazole. The mechanism of formation of the impurity was investigated, and a mechanism is proposed. [ABSTRACT FROM AUTHOR]

Macrophage activation is involved in the outcome of many diseases and is recognized as one of the best targets for disease intervention. Glucomannans had shown promising immunomodulatory potential. Herein, the activation performance of macrophages by glucomannans from different sources was thoroughly investigated. Glucomannans triggered the immune activation of macrophages, which was mainly manifested in increasing the secretion of immune effector molecules, enhancing the endocytosis and phagocytosis of macrophages, and selectively facilitating the expression of M1 phenotype. The participation of NF-κB and MAPK signaling pathways further validated the immune activation of macrophages by glucomannans. Correlation analysis indicated acetyl might be a feasible target for glucomannans to induce immune activation and the molecular weight (M w) of glucomannans was also inseparable from the performance of immune activation. In conclusion, glucomannans showed a moderate immune activation effect on macrophages, and their difference in immune activation was closely related to the acetyl content and M w. [Display omitted] [ABSTRACT FROM AUTHOR]

4-[(3-Acetylphenyl)amino]-2-methylidene-4-oxobutanoic acid is synthesized and the structure of the compound was confirmed by IR, 1 H NMR and single crystal X-ray diffraction studies. FT-IR spectrum of 4-[(3-acetylphenyl)amino]-2-methylidene-4-oxobutanoic acid was recorded and analyzed. The crystal structure is also described. The vibrational wavenumbers were computed using HF and DFT methods are assigned with the help of potential energy distribution analysis. The NH stretching frequency is red shifted in the IR spectrum with a strong intensity from the computed frequency, which indicates the weakening of the NH bond resulting in proton transfer to the neighboring oxygen atom. The first hyperpolarizability and infrared intensities are also reported. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. Molecular electrostatic potential map was performed by the DFT method. The geometrical parameters of the title compound obtained from XRD studies are in agreement with the calculated (DFT) values. [ABSTRACT FROM AUTHOR]

The acetyl ‘capping’ reaction routinely employed during phosphorothioate oligonucleotide synthesis has been implicated in the formation of an impurity species with a mass 41 amu greater than the expected oligonucleotide molecule. The impurity has been found to arise by conversion of a protected guanine nucleobase to N 2 -acetyl-2,6-diaminopurine. A two-part mechanism is proposed consisting of transamidation of the protecting group on guanine and substitution of guanine’s O 6 atom. [ABSTRACT FROM AUTHOR]

Preclinical Research This study describes the anti ‐ inflammatory activities of two semisynthesized melatonin (MT) derivatives, benzoyl ‐ melatonin (BMT) and acetyl ‐ melatonin (AMT), on the production of pro ‐ inflammatory mediators in lipopolysaccharide (LPS) ‐ stimulated macrophage cells (RAW 264.7) and their antinociceptive effects in mice. The MT derivatives inhibited production of nitric oxide NO and prostaglandin E2 in LPS ‐ stimulated RAW264.7 cells in a dose ‐ dependent manner with IC50 values lower than those of MT. BMT produced increased tail flick latency time, decreased number of writhes, and reduced nociceptive response in mice when compared with AMT and MT. BMT and AMT had enhanced anti ‐ inflammatory effects in LPS ‐ stimulated RAW264.7 compared with MT. However, in mouse studies BMT exhibited the highest potency as an anti ‐ inflammatory agent and was longer ‐ acting as an antinociceptive compound compared with AMT or MT, suggesting that BMT has potential as an anti ‐ inflammatory and analgesic compound. [ABSTRACT FROM AUTHOR]

Highlights: [•] 21 Enzyme recalcitrant oligosaccharides from corn fiber are structurally identified. [•] Common structural features: gal-xyl-ara side chains, acetyl-, and feruloyl groups. [•] Branched backbone xylose residues may be acetylated as well. [•] Ethyl glycosides of hemicellulosic structures identified may originate from SSF. [•] Recalcitrant structures identified clearly point to lacking enzyme activities. [Copyright &y& Elsevier]

The kinetics of photooxidation of pyruvate was investigated in presence of zinc oxide catalyst under illumination of visible light. The influence of different parameters such as concentrations of reactants, amount of catalyst and irradiation time was studied on the redox reaction under pseudo-first order conditions. The results indicated that amount of catalyst, presence of electron accepter in solution and irradiation time was the key factors influencing the efficiency of photo-oxidation of pyruvate to acetyl. [ABSTRACT FROM AUTHOR]

Abstract: Variables that influence the citric-acid extraction of pectins from cacao pod husk were examined. A screening study tested the main parameters influencing pectin yield and uronic acid content by a factorial fractional 33−1 design. Further, response surface methodology was applied using a central composite design to examine the effect of a greater region of variable values on pectin yield and uronic acid content. The yield was optimized by increasing the temperature and time. None of the variables had a significant effect on the uronic acid content, and there was lack of fit of the model to the uronic acid content. From the fitted model, extraction conditions with aqueous citric acid at pH 3.0 for 95 min at 95 °C provided a predicted yield of approximately 9.0 g/100 g dry cacao pod husks. The obtained experimental value for the yield was 10.1 ± 0.3 g/100 g dry cacao pod husks, with the pectins containing 65.1 ± 0.8 g uronic acid/100 g fraction, DE 40.3% and DA 15.9%. At 5 g/100 g aqueous solution, the fraction behaved as a concentrated solution and presented a non-Newtonian shear-thinning behavior, well described by Cross Model. Additionally, the fraction formed gels at acidic pH and high sucrose content. [Copyright &y& Elsevier]

Abstract: In the peresent paper, indole and its seven derivatives were compared, namely 3-formylindole, 1-methyl-3-formylindole, 1-ethyl-3-formylindole, 3-acetylindole, 1-methyl-3-acetylindole, 1-ethyl-3-acetylindole and 1,3-diacetylindole. The substitution of indole in position 3 with aldehydes and with alkyl groups cause only minor changes in the molecular geometry, however, substantially larger alterations are found in the charge distribution and in the vibrational force constants. The appearance of the aldhyde groups increased the degree of association as it was observable on the shape of infrared NH stretching band and its shifts. The alkyl substitution shifts the aldehyde carbonyl stretch band frequencies to somewhat higher values. The effect of the second acetyl group in position 1 is not comparable with those of the 1-alkyl groups. The latter effect is observable in the molecular geometry, however, it is more pronounced in the changes of the net charge distribution, the vibrational force constants and the infrared spectra. [Copyright &y& Elsevier]

Abstract: Nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylases (sirtuins) and other enzymes that produce nicotinamide are integral to many cellular processes. Yet current activity measurements involve expensive and time-consuming assays. Here we present a spectroscopic assay that circumvents many issues of previous methods. This assay permits continuous product monitoring over time, allows determination of steady-state kinetic parameters, and is readily adaptable to high-throughput screening. The methodology uses an enzyme-coupled system in which nicotinamide is converted to nicotinic acid and ammonia by nicotinamidase. The ammonia is transferred to α-ketoglutarate via glutamate dehydrogenase, yielding glutamate and the oxidation of NAD(P)H to NAD(P)+, which is measured spectrophotometrically at 340nm. Using this continuous assay with sirtuin-1 (Sirt1) and the ADP-ribosyl cyclase CD38, the resulting steady-state kinetic parameters are in excellent agreement with values obtained by other published methods. Importantly, this assay permitted determination of k cat and K m values with the native acetylated substrate acetyl-CoA synthetase-1; measurement of Sirt1, Sirt2, and Sirt3 activities from mammalian cell extracts; and determination of IC50 values of various Sirt1 inhibitors. This assay is applicable to any nicotinamide-forming enzyme and will be an important tool to address many outstanding questions surrounding their regulation. [Copyright &y& Elsevier]

In order to investigate changes in substrate chemical and physical features after pretreatment, several characterizations were performed on untreated (UT) corn stover and poplar and their solids resulting pretreatments by ammonia fiber expansion (AFEX), ammonia recycled percolation (ARP), controlled pH, dilute acid, flowthrough, lime, and SO2 technologies. In addition to measuring the chemical compositions including acetyl content, physical attributes determined were biomass crystallinity, cellulose degree of polymerization, cellulase adsorption capacity of pretreated solids and enzymatically extracted lignin, copper number, FT-IR responses, scanning electron microscopy (SEM) visualizations, and surface atomic composition by electron spectroscopy of chemical analysis (ESCA). Lime pretreatment removed the most acetyl groups from both corn stover and poplar, while AFEX removed the least. Low pH pretreatments depolymerized cellulose and enhanced biomass crystallinity much more than higher pH approaches. Lime pretreated corn stover solids and flowthrough pretreated poplar solids had the highest cellulase adsorption capacity, while dilute acid pretreated corn stover solids and controlled pH pretreated poplar solids had the least. Furthermore, enzymatically extracted AFEX lignin preparations for both corn stover and poplar had the lowest cellulase adsorption capacity. ESCA results showed that SO2 pretreated solids had the highest surface O/C ratio for poplar, but for corn stover, the highest value was observed for dilute acid pretreatment with a Parr reactor. Although dependent on pretreatment and substrate, FT-IR data showed that along with changes in cross linking and chemical changes, pretreatments may also decrystallize cellulose and change the ratio of crystalline cellulose polymorphs (Iα/Iβ). [Copyright &y& Elsevier]

Analysis of variously pretreated corn stover samples showed neutral to mildly acidic pretreatments were more effective at removing xylan from corn stover and more likely to maintain the acetyl to xylopyranosyl ratios present in untreated material than were alkaline treatments. Retention of acetyl groups in the residual solids resulted in greater resistance to hydrolysis by endoxylanase alone, although the synergistic combination of endoxylanase and acetyl xylan esterase enzymes permitted higher xylan conversions to be observed. Acetyl xylan esterase alone did little to improve hydrolysis by cellulolytic enzymes, although a direct relationship was observed between the enzymatic removal of acetyl groups and improvements in the enzymatic conversion of xylan present in substrates. In all cases, effective xylan conversions were found to significantly improve glucan conversions achievable by cellulolytic enzymes. Additionally, acetyl and xylan removal not only enhanced the respective initial rates of xylan and glucan conversion, but also the overall extents of conversion. This work emphasizes the necessity for xylanolytic enzymes during saccharification processes and specifically for the optimization of acetyl esterase and xylanase synergies when biomass processes include milder pretreatments, such as hot water or sulfite steam explosion. [ABSTRACT FROM AUTHOR]

Alcohol drinking is known to lead to deleterious effects on prostate epithelial cells from humans and experimental animals. The understanding of the mechanisms underlying these effects is relevant to intraprostatic ethanol treatment of benign prostatic hyperplasia and to shed some light into the conflictive results linking alcohol consumption to prostate cancer. In previous studies, we provided evidence about the presence in the rat ventral prostate of cytosolic and microsomal metabolic pathways of ethanol to acetaldehyde and 1-hydroxyethyl radical and about the low levels of alcohol dehydrogenase and aldehyde dehydrogenase. Acetaldehyde accumulation in prostate tissue and oxidative stress promotion were also observed. In this study, we report that in the ventral prostate cytosolic fraction, xanthine oxidoreductase is able to metabolize acetaldehyde to acetyl radical. The identification of the acetyl was performed by GC-MS of the silylated acetyl-PBN adduct. Reference adduct was generated chemically. Formation of acetyl was also observed using pure xanthine oxidase. The generation of acetyl by the prostate cytosol was inhibited by allopurinol, oxypurinol, diphenyleneiodonium chloride, folate, and ellagic acid. Results suggest that metabolism of ethanol to acetaldehyde and to 1-hydroxyethyl and acetyl radicals could be involved in the deleterious effects of alcohol drinking on prostate epithelial cells. [ABSTRACT FROM AUTHOR]

Pentosan Polysulfate Sodium (PPS) is a semi-synthetic polysulfated xylan sourced from beechwood tree barks. PPS, which is mainly composed of a xylose chain with branched O-methyl-glucuronate (MGA), can have heterogeneity in monosaccharide species, sequence and chemical modifications including sulfation and acetylation. The monosaccharide composition in polysaccharide therapeutics is a frequently quoted quality attribute (QA), which has been assessed using two-dimensional (2D) 1H–13C HSQC NMR. However, the sensitivity of 2D NMR for the assessment of PPS inter-lot variability from the same manufacturer was unclear and questions remained whether 2D NMR had sufficient sensitivity to distinguish normal batch to batch variations in this QA. Here, a 2D peak profile method was applied to compare high-resolution semi-quantitative (semi-q) HSQC spectra with the inclusion of intermediate precision spectra collected on two PPS drug lots released 29 months apart (where one of the lots was expired). The semi-q HSQC NMR confirmed the mass equivalence of total polysaccharides, O-Methyl and acetyl groups between the two lots. The 2D spectral peak profile results readily identified significant lot-to-lot differences (p < 0.05) in relative distribution among most monosaccharide species, in addition to heterogeneity in MGA distribution and acetyl transfer from PPS to free acetate in the expired lot. Precisely measured chemical QAs are prerequisites to establish normal batch variation in the innovator product, providing important reference ranges for complex generic drug developers. Overall, high-resolution semi-q HSQC NMR may provide a sensitive tool to measure fine chemical differences in polysaccharide therapeutics needed to establish chemical QAs and compare batches without concerns of intrinsic NMR method variation. • 2D HSQC NMR was applied to measure chemical composition of Pentosan Polysulfate Sodium (PPS). • 2D peak profile method differentiated the two batches of PPS in monosaccharide composition. • The PPS-linked acetyl hydrolysis was observed in the expired PPS lot. • 2D NMR can be used toward establishing normal range of batch-to-batch variation. [ABSTRACT FROM AUTHOR]

Abstract: (η5-methylcyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt (1) and its derivatives, [(1-acetyl-2-methyl)η5-cyclopentadienyl](η4-tetraphenylcyclobutadiene)cobalt (2) [(1-acetyl-3-methyl)η5-cyclopentadienyl](η4-tetraphenylcyclobutadiene)cobalt (3) [(1-carbomethoxy-2-methyl)η5-cyclopentadienyl](η4-tetraphenylcyclobutadiene)cobalt (4) and [(1-carbomethoxy-3-methyl)η5-cyclopentadienyl](η4-tetraphenylcyclobutadiene) cobalt (5) have been prepared in yields varying from 11% to 28% by introducing the substituents on the cyclopentadienyl ring of methylcyclopentadienyl sodium and then reacting with diphenylacetylene and CoCl(PPh3)3. The carboxylic acids [(1-carboxy-2-methyl)η5-cyclopentadienyl](η4-tetraphenylcyclobutadiene)cobalt (6), [(1-carboxy-3-methyl)η5-cyclopentadienyl](η4-tetraphenylcyclobutadiene)cobalt (7) have been prepared after ester hydrolysis of compounds 4 and 5 using KOH/ethanol. [(1-dimethylaminomethyl-3-methyl)η5-cyclopentadienyl](η4-tetraphenylcyclobutadiene) cobalt (8), was prepared selectively by direct substitution on the cyclopentadienyl ring of (η5-methylcyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt in 65% yield. The 1,2-isomer was formed only in traces in this reaction. Reactivity of (η5-methylcyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt and its carbomethoxy derivative have been compared with (η5-cyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt. All new compounds were characterized by 1H and 13C NMR, FT-IR, mass spectra and CHN analysis. Compounds 2, 4, 6 and 8 have also been structurally characterized by single crystal X-ray structural analysis. [Copyright &y& Elsevier]

3-Oxo-2-[(Z)-1-phenylmethylidene]-5H-[1,3]thiazolo[3,2-a] pyrimidine derivatives 2a-f were synthesized by the reaction of an appropriate 3,4-dihydro-2(H)-pyrimidone 1, chloroacetic acid, sodium acetate and benzaldehyde. Reaction of 1 with acetic anhydride under heating afforded only 3-N-acetylated 3,4-dihydro-2(H)-pyrimidines 3a-f. The yields of the products after recrystallization from ethanol were of the order of 60-92 %. IR, 1H NMR spectroscopy, and elemental analysis were used for the identification of these compounds. [ABSTRACT FROM AUTHOR]

Abstract: The enzymatic depolymerization of a nascent high O-acetylated glucuronan has been studied to envisage and evaluate a possible O-acetylated oligouronides production and purification process. This paper investigates the significance of the operating parameters for the large production of anionic O-acetylated-oligosaccharides with degree of polymerization up to 10 produced by degradation of bacterial O-acetylated-β-(1,4)-d-polyglucuronic using a glucuronan lyase (GL2) from Trichoderma sp. During the glucuronan biosynthesis none oligosaccharide was obtained even if the glucuronan lyase was added before or at the end of the glucuronan biosynthesis. In such conditions, just O-acetylated MMWs and LMWs with dp>10 were recovered. However, polymeric families with molecular weight lower than 100kDa and partially purified using tangential ultrafiltration (UFT) were totally degraded into oligosaccharides. All these oligouronides were isolated, fractionated by low-pressure size liquid chromatography and characterized by NMR spectroscopy to apprehend their O-acetyl distribution and degree of polymerization. This study allows the production of O-acetylated oligoglucuronan in order to envisage new therapeutic applications fields such as the realization of biological tests among animals and vegetals. [Copyright &y& Elsevier]

2‐Acetamido‐2‐deoxy‐β‐D‐mannopyranose (1) was glycosylated by the Fischer method using an acidic ion‐exchange resin as the catalyst to give α‐methyl glycoside 2. Selective pivaloylations of methyl 2‐acetamido‐2‐deoxy‐α‐D‐mannopyranoside (2) have been studied under various reaction conditions. Two partially pivaloylated products were submitted to additional acetylations. All structures were established by NMR spectroscopy. Structure of the methyl 2‐acetamido‐2‐deoxy‐3,6‐di‐O‐pivaloyl‐α‐D‐mannopyranoside (4) was determined by X‐ray analysis. [ABSTRACT FROM AUTHOR]

Abstract: Corn stover was pretreated with excess calcium hydroxide (0.5g Ca(OH)2/g raw biomass) in non-oxidative and oxidative conditions at 25, 35, 45, and 55°C. The enzymatic digestibility of lime-treated corn stover was affected by the change of structural features (acetylation, lignification, and crystallization) resulting from the treatment. Extensive delignification required oxidative treatment and additional consumption of lime (up to 0.17g Ca(OH)2/g biomass). Deacetylation reached a plateau within 1week and there were no significant differences between non-oxidative and oxidative conditions at 55°C; both conditions removed approximately 90% of the acetyl groups in 1week at all temperatures studied. Delignification highly depended on temperature and the presence of oxygen. Lignin and hemicellulose were selectively removed (or solubilized), but cellulose was not affected by lime pretreatment in mild temperatures (25–55°C), even though corn stover was contacted with alkali for a long time, 16weeks. The degree of crystallinity slightly increased from 43% to 60% with delignification because amorphous components (lignin, hemicellulose) were removed. However, the increased crystallinity did not negatively affect the 3-d sugar yield of enzymatic hydrolysis. Oxidative lime pretreatment lowered the acetyl and lignin contents to obtain high digestibility, regardless of crystallinity. The non-linear models for 3-d hydrolysis yields of glucan (Y g), xylan (Y x), and holocellulose (Y gx) were empirically established as a function of the residual lignin (L) for the corn stover pretreated with lime and air. [Copyright &y& Elsevier]

We investigated the feasibility of formation of the C2H3O+ chemiion during collisions of O(3P) with the CH3C (ã4A2), CH2CH (ã4A″), CH3C (X2A″), and CH2CH (X2A′) radicals, which are possible intermediates in the oxidation of 2-butyne. We determined the C–O bond dissociation energies and the ionization energies of the neutral C2H3O species as well as the C–O bond dissociation energies of C2H3O+. We conclude that the CH3C (ã4A2) radical is the most probable precursor of the chemiion, in agreement with experimental evidence. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [ABSTRACT FROM AUTHOR]

Abstract: Polysaccharides were extracted from green Coffea arabica beans with water (90°C, 1h). Galactomannans were isolated from the water extract using preparative anion-exchange chromatography. Almost all of the galactomannans eluted in two neutral populations, while almost all of the arabinogalactans bound to the column, indicating that these arabinogalactans contain charged groups. Analysis of the molecular weight distribution of the two neutral populations showed that they differ in their molecular weight. Further characterization of these neutral populations by NMR and by MALDI-TOF MS after enzymatic degradation with an endo-mannanase, showed the presence of acetyl groups linked to the galactomannans, a feature not previously described for this type of polysaccharides from coffee beans. It was found that the high molecular weight (ca. 2000kDa) neutral fraction was highly substituted both with galactose residues and acetyl groups, while the low molecular weight (ca. 20kDa) population was much less substituted. Based on these results it can be concluded that at least two distinctly different populations of galactomannans are present in green coffee beans. It was also shown that the degradation of the galactomannans from green coffee beans with an endo-mannanase from A. niger is hindered by the presence of acetyl groups. [Copyright &y& Elsevier]