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Protein methyl groups can participate in multiple motional modes on different time scales. Sub-nanosecond to nano-second time scale motions of methyl axes are particularly challenging to detect for small proteins in solutions. In this work we employ NMR relaxation interference between the methyl H-H/H-C dipole-dipole interactions [Sun&Tugarinov, J. Magn. Reason. 2012] to characterize methyl axes motions as a function of temperature in a small model protein villin headpiece subdomain (HP36), in which all non-exchangeable protons are deuterated with the exception of methyl groups of leucine and valine residues. The data points to the existence of slow motional modes of methyl axes on sub-nanosecond to nanosecond time scales. Further, at high temperatures for which the overall tumbling of the protein is on the order of 2 ns, we observe a coupling between the slow internal motion and the overall molecular tumbling, based on the anomalous order parameters and their temperature-dependent trends. The addition of 28%(w/w) glycerol-d8 increases the viscosity of the solvent and separates the timescales of internal and overall tumbling, thus permitting for another view of the necessity of the coupling assumption for these sites at high temperatures.

International audience; HSP90 is a major molecular chaperone that helps both folding and stabilization of various client proteins often implicated in growth control and cell survival such as kinases and transcription factors. However, among HSP90 clients are also found numerous oncoproteins and, through its assistance to them, HSP90 has consequently been reported as a promising anticancer target. Several ligand chemotypes, including resorcinol type ligands, were found to inhibit HSP90, most of them in an ATP competitive manner. Binding of some of these ligands modify significantly the NMR spectrum of the HSP90 ATP binding domain compared to the apo protein spectrum, hampering assignment transfer from the previously assigned human HSP90 apo state. Here we report the assignment of the 1HN, 15N, 13C', 13Cα, 13Cβ, 1Hmethyl, and 13Cmethyl chemical shifts of the 29 kDa HSP90 N-terminal domain bound to a long residence time resorcinol type inhibitor: 5-[4-(2-Fluoro-phenyl)-5-oxo-4,5-dihydro-1H-[1,2,4]triazol-3-yl]-N-furan-2-ylmethyl-2,4-dihydroxy-N-methyl-benzamide. 92% of the backbone resonances and 100% of the [1H, 13C]-resonances of Aβ, Mε, Tγ, Lδ2, Vγ2 and Iδ1 methyl groups were successfully assigned, including for the first time the assignment of the segment covering the nucleotide/drug binding site. Secondary structure predictions based on the NMR assignment reveal a structural rearrangement of HSP90 N-terminal domain upon ligand binding. The long residence time ligand induces the formation of a continuous helix covering the ligand binding site of HSP90 N-terminal domain accounting for the large differences observed in the NMR spectra between the apo and bound proteins.

Este artículo se encuentra disponible en la siguiente URL: https://www.mdpi.com/2227-9059/10/4/866 Este artículo de investigación pertenece al número especial "Cellular Mechanisms of Cardiovascular Disease". A controversial understanding of the state of the DNA methylation machinery exists in ischaemic cardiomyopathy (ICM). Moreover, its relationship to other epigenetic alterations is incomplete. Therefore, we carried out an in-depth study of the DNA methylation process in human cardiac tissue. We showed a dysregulation of the DNA methylation machinery accordingly with the genome-wide hypomethylation that we observed: specifically, an overexpression of main genes involved in the elimination of methyl groups (TET1, SMUG1), and underexpression of molecules implicated in the maintenance of methylation (MBD2, UHRF1). By contrast, we found DNMT3B upregulation, a key molecule in the addition of methyl residues in DNA, and an underexpression of miR-133a-3p, an inhibitor of DNMT3B transcription. However, we found many relevant alterations that would counteract the upregulation observed, such as the overexpression of TRAF6, responsible for Dnmt3b degradation. Furthermore, we showed that molecules regulating Dnmts activity were altered; specifically, SAM/SAH ratio reduction. All these results are in concordance with the Dnmts normal function that we show. Our analysis revealed genome-wide hypomethylation along with dysregulation in the mechanisms of addition, elimination and maintenance of methyl groups in the DNA of ICM. We describe relevant alterations in the DNMT3B system, which promote a normal Dnmt3b function despite its upregulation.

Methyl groups are found in numerous biogenic and synthetic materials including geologically preserved materials such as wood. The carbon and hydrogen isotope compositions of methyl groups are used as tracers in biogeochemical cycles, as paleothermometers, and to determine the hydrogen isotopic composition of ancient rain. Here we present analyses of resolved 13C–D (13CH2D) and D–D (12CHD2) clumped isotope compositions of methyl groups as new variables for the study of methyl groups in the present and past. We first present chemical methods to extract, purify, and derivatize methyl groups from methoxyl (R–O–CH3) groups as CH3F and CH3Cl, and high-resolution mass spectrometric techniques to determine the clumped isotope compositions of these species. We achieve precisions for 13C–D clumping of ±0.25‰ and D–D clumping of ±2.5‰. We anchor our clumped isotopic measurements to a thermodynamic reference frame by first calculating the theoretical temperature dependences of 13C–D and D–D clumping in CH3Cl, then placing our measurements onto this reference frame through experimental internal isotopic equilibration of CH3Cl at 200 °C. Finally, we provide and analyze an initial dataset of clumped 13C–D and D–D compositions of methyl groups from various commercial/synthetic monomers and environmental woods. We observe ranges in clumped isotope compositions of ∼11‰ in 13C–D and ∼48‰ in D–D, and systematic differences within these ranges between methyl groups from commercial monomers and wood. Specifically, commercial clumped 13C–D compositions are between 0 and 3‰, which correspond to apparent equilibrium temperatures between 170 °C and the infinite temperature limit. In contrast, the clumped 13C–D compositions of wood methoxyl groups are distinctively high (9.50–11.25‰) and 3–6‰ higher than would be expected if formed in internal isotopic equilibrium at Earth-surface temperatures. Commercial/synthetic methyl and wood methoxyl clumped D–D compositions are also distinct: −5 to +13‰ in commercial monomers vs. −35 to −8‰ in wood—such negative values cannot result from formation in isotopic equilibrium and require kinetic processes to have occurred. These results indicate that wood methoxyl groups are formed out of isotopic equilibrium and that clumped isotope compositions of methyl groups may be useful tracers of methyl group sources and sinks in the environment. For instance, isotopic clumping in methyl groups may be useful for understanding controls on isotopic clumping in methane produced by methylotrophic methanogens.

International audience; Methyl moieties are highly valuable probes for quantitative NMR studies of large proteins. Hence, their assignment is of the utmost interest to obtain information on both interactions and dynamics of proteins in solution. Here, we present the synthesis of a new precursor that allows connection of leucine and valine pro-S methyl moieties to backbone atoms by linear 13C-chains. This optimized 2H/13C-labelled acetolactate precursor can be combined with existing 13C/2H-alanine and isoleucine precursors in order to directly transfer backbone assignment to the corresponding methyl groups. Using this simple approach leucine and valine pro-S methyl groups can be assigned using a single sample without requiring correction of 1H/2H isotopic shifts on 13C resonances. The approach was demonstrated on the N-terminal domain of human HSP90, for which complete assignment of Ala-β, Ile-δ1, Leu-δ2, Met-ε, Thr-γ and Val-γ2 methyl groups was obtained.

The use of betaine associated or not with choline chloride 70% in Japanese quail diets in the laying phase was evaluated. 504 Japanese quails (Coturnix cortunix Japonica) were used from 104 to 208 days old, in a 3x2 + 1 factorial design, completely randomized design, seven treatments, nine replications, eight birds per experimental unit. Betaine was supplemented in 20% of the digestible methionine level of the control diet, in diets with reformulated betaine the level of enrichment was in the nutritional matrix of the product (100%) and with an extra recovery of 5% (105%). Choline chloride was fixed at 0.07%. Productive performance, egg quality, histometry, and the number of goblet cells from the duodenum and hepatic glycogen were analyzed. The use of betaine promoted greater weight of the eggs to the control, regardless of the mode of use, the use of choline promoted a superior result in the weight of the eggs. In egg quality, only shell percentage was influenced. The use of the reformulated betaine 100% of the matrix promoted greater height of the villi, and a lower villus: crypt ratio to the treatment with the reformulation enriched by 105%. Hepatic glycogen was not influenced. In goblet cells, the reformulation in an extra 105% of the matrix was superior to the matrix in 100%. The hill reduced villus height, improved villus: crypt ratio, and number of goblet cells. In conclusion, the reformulated betaine enriched in an additional 5% of its nutritional matrix replaces the use of choline chloride in the laying of Japanese quail diets. Se evaluó el uso de betaína asociada o no con cloruro de colina al 70% en dietas de codorniz japonesa en la fase de puesta. Se utilizaron 504 codornices japonesas (Coturnix cortunix Japonica) de 104 a 208 días de edad, en un diseño factorial 3x2 + 1, diseño completamente al azar, siete tratamientos, nueve repeticiones, ocho aves por unidad experimental. La betaína se complementó en un 20% del nivel de metionina digerible de la dieta de control, en las dietas con betaína reformulada el nivel de enriquecimiento se encontraba en la matriz nutricional del producto (100%) y con una recuperación adicional del 5% (105%). El cloruro de colina se fijó al 0,07%. Se analizó el rendimiento productivo, la calidad del huevo, la histometría y el número de células caliciformes del duodeno y el glucógeno hepático. El uso de betaína promovió un mayor peso de los huevos al control, independientemente del modo de uso, el uso de colina promovió un resultado superior en el peso de los huevos. En la calidad del huevo, solo el porcentaje de cascarón fue influenciado. El uso de la betaína reformulada al 100% de la matriz promovió una mayor altura de las vellosidades, y una relación vellosidad: cripta más baja al tratamiento con la reformulación enriquecida en un 105%. El glucógeno hepático no fue influenciado. En las células caliciformes, la reformulación en un 105% adicional de la matriz fue superior a la matriz en un 100%. La colina redujo la altura de las vellosidades, mejoró la relación vellosidad: cripta y el número de células caliciformes. En conclusión, la betaína reformulada enriquecida en un 5% adicional de su matriz nutricional reemplaza el uso de cloruro de colina en la colocación de las dietas japonesas de codorniz. Avaliou-se o uso da betaína associada ou não com cloreto de colina 70% em rações de codornas japonesas na fase de postura. Foram utilizadas 504 codornas japonesas (Coturnix cortunix Japonica) de 104 a 208 dias de idade, em esquema fatorial 3x2+1, delineamento inteiramente casualizado, sete tratamentos, nove repetições, oito aves por unidade experimental. A betaína foi suplementada em 20% do nível de metionina digestível da dieta controle, nas dietas com betaína reformulada o nível de enriquecimento foi da matriz nutricional do produto (100%) e com valorização extra de 5% (105%). O cloreto de colina foi fixado em 0,07%. Analisou-se desempenho produtivo, qualidade de ovos, histometria e número de células caliciformes do duodeno e glicogênio hepático. O uso da betaína promoveu maior peso dos ovos em relação ao controle, independentemente do modo de uso, o uso da colina promoveu resultado superior no peso dos ovos. Na qualidade dos ovos, somente percentual de casca foi influenciado. O uso da betaína reformulada 100% da matriz promoveu maior altura dos vilos, e menor relação vilo:cripta em relação ao tratamento com a reformulação enriquecida em 105%. O glicogênio hepático não foi influenciado. Nas células caliciformes, a reformulação em 105% extras da matriz foi superior a matriz em 100%. A colina reduziu altura dos vilos, melhorou relação vilo:cripta e número de células caliciformes. Em conclusão, a betaína reformulada enriquecida em mais 5% de sua matriz nutricional substitui o uso de cloreto de colina nas rações de codornas japonesas em postura.

International audience; Specific isotopic labeling of methyl groups in a perdeuterated protein background enables the detection of long range NOEs in proteins or high molecular weight complexes. We introduce here an approach, combining an optimized isotopic labeling scheme with a specifically tailored NMR pulse sequence, to distinguish between intramolecular and intermolecular NOE connectivities. In hetero-oligomeric complexes, this strategy enables sign encoding of intra-subunit and inter-subunit NOEs. For homo-oligomeric assemblies, our strategy allows the specific detection of intra-chain NOEs in high resolution 3D NOESY spectra. The general principles, possibilities and limitations of this approach are presented. Applications of this approach for the detection of intermolecular NOEs in a hetero-hexamer, and the assignment of methyl 1H and 13C resonances in a homo-tetrameric protein complex are shown.

International audience; This paper is a review of molecules with internal rotors detected or tentatively detected with upper limits in the interstellar medium. Internal rotor molecules containing one or two methyl groups are present at each of the different phases leading to stellar and planetary formation, from the molecular clouds to the star and its planets. They are also found in comets and asteroids. They represent a ubiquitous hydrogen-rich substituent in many complex organic molecules. This paper shows how high resolution spectra (mainly in the microwave, millimeter and sub-millimeter wave range) are analyzed in the laboratory and what theoretical methods can be used to properly reproduce the spectra. We also present a range of examples of important methyl rotors studied and how they can be used as tools to study the chemistry of interstellar medium.

The effect of fine wheat bran (FWB) as a methyl donor source on performance, metabolism, body composition and blood traits of growing broilers was studied. Three hundred and twenty broilers from eight to 28 d of age, distributed in a randomized block design, with five treatments and eight replicates of eight animals each were used. The experimental diets were: NC, formulated with 72% of the Met+Cys requirement; Met, formulated with 85% of the Met+Cys equivalents by DL-methionine addition; Bet, formulated with 85% of the Met+Cys equivalents by anhydrous betaine addition; Fwb-, formulated with 72% of the Met+Cys requirement and 20% FWB; and Fwb+, formulated with 85% of the Met+Cys requirement and 20% FWB. Feed intake was reduced (p0.05) between the positive control diets. Supplementation of DL-methionine and anhydrous betaine showed the same (p>0.05) metabolizability of nutrients. Treatments with higher DL-methionine levels (Met and Fwb+) promoted more weight of feathers (p

The effect of fine wheat bran (FWB) as a methyl donor source on performance, metabolism, body composition and blood traits of growing broilers was studied. Three hundred and twenty broilers from eight to 28 d of age, distributed in a randomized block design, with five treatments and eight replicates of eight animals each were used. The experimental diets were: NC, formulated with 72% of the Met+Cys requirement; Met, formulated with 85% of the Met+Cys equivalents by DL-methionine addition; Bet, formulated with 85% of the Met+Cys equivalents by anhydrous betaine addition; Fwb-, formulated with 72% of the Met+Cys requirement and 20% FWB; and Fwb+, formulated with 85% of the Met+Cys requirement and 20% FWB. Feed intake was reduced (p0.05) between the positive control diets. Supplementation of DL-methionine and anhydrous betaine showed the same (p>0.05) metabolizability of nutrients. Treatments with higher DL-methionine levels (Met and Fwb+) promoted more weight of feathers (p

Liquid-state NMR spectroscopy is a powerful technique to elucidate binding properties of ligands on proteins. Ligands binding in hydrophobic pockets are often in close proximity to methyl groups and binding can lead to subtle displacements of methyl containing side chains to accommodate the ligand. To establish whether pseudocontact shifts can be used to characterize ligand binding and the effects on methyl groups, the N-terminal domain of HSP90 was tagged with caged lanthanoid NMR probe 5 at three positions and titrated with a ligand. Binding was monitored using the resonances of leucine and valine methyl groups. The pseudocontact shifts (PCS) caused by ytterbium result in enhanced dispersion of the methyl spectrum, allowing more resonances to be observed. The effects of tag attachment on the spectrum and ligand binding are small. Significant changes in PCS were observed upon ligand binding, indicating displacements of several methyl groups. By determining the cross-section of PCS iso-surfaces generated by two or three paramagnetic centers, the new position of a methyl group can be estimated, showing displacements in the range of 1–3 Å for methyl groups in the binding site. The information about such subtle but significant changes may be used to improve docking studies and can find application in fragment-based drug discovery. Electronic supplementary material The online version of this article (10.1007/s10858-018-0190-5) contains supplementary material, which is available to authorized users.

International audience; Quantum-rotor-induced polarisation (QRIP) enhancement is exhibited by substances which contain freely rotating methyl groups in the solid state, provided that the methyl groups contain a (13)C nucleus. Strong signal enhancements are observed in solution NMR when the material is first equilibrated at cryogenic temperatures, then rapidly dissolved with a warm solvent and transferred into an NMR magnet. QRIP leads to strongly-enhanced (13)C NMR signals, but relatively weak enhancements of the (1)H signals. We show that the (1)H signals suffer from a partial cancellation of degenerate contributions, which may be corrected by applying a frequency-selective π pulse to the inner peaks of the (13)C multiplet prior to (1)H observation.

We propose a proof-of-principle experiment to encode one logical qubit in noise protected subspace of three identical spins in a methyl group. The symmetry analysis of the wavefunction shows that this fermionic system exhibits a symmetry correlation between the spatial degree of freedom and the spin degree of freedom. We show that one can use this correlation to populate the noiseless subsystem by relying on the interaction between the electric dipole moment of the methyl group with a circularly polarized microwave field. Logical gates are implemented by controlling both the intensity and phase of the applied field., 10 pages and 4 figures

Spherical silica particles with bifunctional (≡Si(CH2)3NH2/≡SiCH3, ≡Si(CH2)3NH2/≡Si(CH2)2(CF2)5CF3) surface layers were produced by a one-step approach using a modified Stöber method in three-component alkoxysilane systems, resulting in greatly increased contents of functional components. The content of functional groups and thermal stability of the surface layers were analyzed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and 13C and 29Si solid-state NMR spectroscopy revealing their composition and organization. The fine chemical structure of the surface in the produced hybrid adsorbent particles and the ligand distribution were further investigated by electron paramagnetic resonance (EPR) and electron spectroscopy of diffuse reflectance (ESDR) spectroscopy using Cu2+ ion coordination as a probe. The composition and structure of the emerging surface complexes were determined and used to provide an insight into the molecular structure of the surfaces. It was demonstrated that the introduction of short hydrophobic (methyl) groups improves the kinetic characteristics of the samples during the sorption of copper(II) ions and promotes fixation of aminopropyl groups on the surface of silica microspheres. The introduction of long hydrophobic (perfluoroctyl) groups changes the nature of the surface, where they are arranged in alternately hydrophobic/hydrophilic patches. This makes the aminopropyl groups huddled and less active in the sorption of metal cations. The size and aggregation/morphology of obtained particles was optimized controlling the synthesis conditions, such as concentrations of reactants, basicity of the medium, and the process temperature.

Sufficient dietary fibre intake reduces the risk of several diseases, but the mechanisms linking fibre structure and health effects remain unclear. To analyse the influence of the amount of methyl groups esterified to the backbone, lemon pectins of different degrees of methyl esterification (30, 56, and 74DM) were studied for immune receptor activating potential and epithelial barrier protection. In reporter assays, the pectins demonstrated TLR/MyD88 dependent activation of NF-kappa B/AP-1, which increased with increasing pectin DM. To analyse the importance of backbone structure, the pectins were enzymatically digested into oligomers, which abrogated TLR activating potential. The 30 and 74DM pectins induced strong protection of the epithelial barrier measured by T84 transepithelial electrical resistance (TEER). These results indicate that activation of immune cells by lemon pectins is TLR dependent, and the intact polymer backbone is indispensable for activation. In addition, DM is a determining factor in activating potential and epithelial barrier protective effects. (C) 2016 Elsevier Ltd. All rights reserved.

International audience; A 2D C-13 Chemical Exchange Saturation Transfer (CEST) experiment is presented for studying slowly exchanging protein systems using methyl groups as probes. The utility of the method is first established through studies of protein L, a small protein, for which chemical exchange on the millisecond time-scale is not observed. Subsequently the approach is applied to a folding exchange reaction of a G48M mutant Fyn SH3 domain, for which only cross-peaks derived from the folded ('ground') state are present in spectra. Fits of N-15 and methyl C-13 CEST profiles of the Fyn SH3 domain establish that the exchange reaction involves an interchange between folded and unfolded conformers, although elevated methyl C-13 transverse relaxation rates for some of the residues of the unfolded ('invisible, excited') state indicate that it likely exchanges with a third conformation as well. In addition to the kinetics of the exchange reaction, methyl carbon chemical shifts of the excited state are also obtained from analysis of the C-13 CEST data.

International audience; The specific protonation of valine and leucine methyl groups in proteins is typically achieved by overexpressing proteins in M9/D2O medium supplemented with either labeled α-ketoisovalerate for the labeling of the four prochiral methyl groups or with 2-acetolactate for the stereospecific labeling of the valine and leucine side chains. However, when these labeling schemes are applied to large protein assemblies, significant overlap between the correlations of the valine and leucine methyl groups occurs, hampering the analysis of 2D methyl-TROSY spectra. Analysis of the leucine and valine biosynthesis pathways revealed that the incorporation of labeled precursors in the leucine pathway can be inhibited by the addition of exogenous l-leucine-d10. We exploited this property to label stereospecifically the pro-R and pro-S methyl groups of valine with minimal scrambling to the leucine residues. This new labeling protocol was applied to the 468 kDa homododecameric peptidase TET2 to decrease the complexity of its NMR spectra. All of the pro-S valine methyl resonances of TET2 were assigned by combining mutagenesis with this innovative labeling approach. The assignments were transferred to the pro-R groups using an optimally labeled sample and a set of triple resonance experiments. This improved labeling scheme enables us to overcome the main limitation of overcrowding in the NMR spectra of prochiral methyl groups, which is a prerequisite for the site-specific measurement of the structural and dynamic parameters or for the study of interactions in very large protein assemblies.

Interactions of 5,6-dimethyl- (1), 3,5,6-trimethylthieno[2,3-d]pyrimidin-4(3H)-ones (2) and 2,3-dimethyl- (5-7), 2-methyl-3-methoxycarbonylthieno[2,3-d]dihydropyrrolo-, - tetrahydropyrido-, tetrahydroazepino[1,2-a]pyrimidin-4-ones (14-16) with nitrating mixture were investigated. For the first time it is shown, that in dependence on the presence of substituent in position 2 and 3 of pyrimidine and thiophene rings reaction goes in various directions; by electrophilic ipso-substitution of methyl groups at C-5 by nitro group, or its oxidation up to carboxyl groups with formation corresponding 5-carboxy derivatives. It is revealed, that at absence of the substituent in position 3 (compound 1) the electrophilic ipso-substitution of methyl group by nitro group with formation of 5-nitro derivative took place. It is found, that at interaction of compounds 2,5-7, 14-16 with nitrating mixture instead of substitution of methyl groups at C-2, goes in an unexpected direction, i.e. there are oxidation of methyl groups or electrophilic ipso-substitution of methoxycarbonyl groups in position 3 by nitro group.

Protein methyl groups have recently been the subject of much attention in NMR spectroscopy because of the opportunities that they provide to obtain information about the structure and dynamics of proteins and protein complexes. With the advent of selective labeling schemes, methyl groups are particularly interesting in the context of chemical shift based protein structure determination, an approach that to date has exploited primarily the mapping between protein structures and backbone chemical shifts. In order to extend the scope of chemical shifts for structure determination, we present here the CH3Shift method of performing structure-based predictions of methyl chemical shifts. The terms considered in the predictions take account of ring current, magnetic anisotropy, electric field, rota- meric type, and dihedral angle effects, which are consid- ered in conjunction with polynomial functions of interatomic distances. We show that the CH3Shift method achieves an accuracy in the predictions that ranges from 0.133 to 0.198 ppm for 1H chemical shifts for Ala, Thr, Val, Leu and Ile methyl groups. We illustrate the use of the method by assessing the accuracy of side-chain structures in structural ensembles representing the dynamics of proteins.

Unpretreated (PP-UT) and thermally pretreated (at 80 �C for 10 days) polypropylene (PP-TT) films of 0.05 mm thickness were subjected to in vitro biodegradation in minimal medium with mixed soil culture for 12 months. In this period 10.7 and 0.4% weight loss was observed with PP-TT and PP-UT, respectively. The tensile strength decreased by 51.8 and 28.3%, the crystallinity increased by 28 and 33% and isotacticity increased by 3 and 9%, respectively, over the same time period. The ester carbonyl index in PP-TT increased up to 9 months and later decreased indicating abiotic followed by biotic process. No such changes were observed with PP-UT. Methyl group index decreased in both the cases indicating oxidation at the primary carbon. Increase in surface energy indicated that the polymer became hydrophilic. Surface changes were observed by SEM and AFM. A single culture was isolated at the end of 12 months and it was identified as Bacillus flexus. The morphology of the organism was rods in a chain and it was present in the form of an endospore. � 2008 Elsevier Ltd. All rights reserved.

Thesis (Master)--Izmir Institute of Technology, Chemical Engineering, Izmir, 2008, Includes bibliographical references (leaves: 40-43), Text in English; Abstract: Turkish and English, viii, 43 leaves, In this study, the activities of heterogeneous mixed oxide catalysts; magnesium and calcium oxide on alumina and silica supports were investigated for transesterification of vegetable oils; canola and sunflower, to methyl esters. The primary objective of this study is to understand whether basicity of the solid catalysts and/or its crystallite size affect the biodiesel yield during the reaction. The mixed oxide catalysts were prepared by a single step sol-gel method. Magnesium oxide (MgO) and calcium oxide (CaO) were chosen because of their basic property.This study shows that the crystallite size does not have any direct effect on the transesterification activity. Yet, the interaction of the crystallites with the support material may change the number of the active sites and/or the creation of new .basic. sites. In fact, the basicity was found as the critical factor for the choice of the suitable mixed oxide for the transesterification reaction. The addition of CaO to alumina creates synergetic effect. But this is not observed with the catalysts: CaO/SiO2 and also the MgO/Al2O3 and MgO/SiO2.CaO/Al2O3 differs from the others in such a way that it contains the basic sites with the mild basic strength. Not only the crystallite size but also the type of the oxide is important to obtain the heterogeneous catalysts as active as the homogeneous catalyst. CaO/Al2O3 has the same activity as that of NaOH for the transesterification of canola and sunflower oils at 50 oC. It was also found that the activity of CaO/Al2O3 was truly heterogeneous.

The thermal average molecular structure of Me3TiCp★ has been determined by gas phase electron diffraction (GED). The GED data are consistent with a molecular model in which the TiMe3 fragment has C3v symmetry and the TiCp★ fragment has C5v symmetry. No static tilt of the methyl groups attached to titanium can be detected, although a flattening of the methyl groups with Ti-C-H 103.8(1.2)° is obtained. The Ti-C(Me) bond distance is 210.7(5) pm, and the Ti-C(Cp★) distance 238.0(5) pm., Norwegian Research Council for Science and Humanities, VISTA program

Department of Medicinal Chemistry, I.M.S., Banaras Hindu University, Varanasi-221 005, India E-mail : sajeli I @rediffmail.com Fax : 91-542-2307547 Manuscript received 3 September 2003, accepted 2 December 2003 Four new acyl sucroses, isolated from Petuniα nyctαginiflorα Juss. (Solanaceae) were characterised as 2,3,4- trihexanoyl-α-D- glucopyranosyl- β- D-fructofuranoside, 2,3,4-triheptanoyl-α-D-glucopyranosyl 1-β- D-fructofuranoside, 2,3,4-trihexanoyl-α-D-glucopyranosyl-β- D-6- acetyI fructofuranoside, 2,3,4-triheptanoyl-α-D-glucopyranosyl-β- D- 6- acetyl fructofuranoside, on the basis of chemical and spectroscopic evidence.

Galaxy Research Centre, Galaxy Surfactants Ltd., C-49/2, TTC Industrial Area, Pawne, Navi Mumbai-400 703, India E-mail : Nirmai.Koshti@ galaxysurfactants.com Manuscript received 8 October 2002, revised 3 November 2003, accepted 14 November 2003 Facile synthesis of water-soluble poly(N-isopropyl acrylamide) bound chelators is reported. These polymeric chelators have a lower critical solution temperature (LCST) and quantitatively phase·separate on heating. Their utility in metal removal and recycling is demonstrated with hydroxamic acid as ligand and Fe3+ as metal ion.

H. E. J. Research Institute or Chemistry University ofKarachi, Karachi-32, Pakistan Manuscript received 11 January 1988, revised 14 March 1988,accepted 21 March 1988 A New Withanolide Datumetelin from the Leaves of Datura metel L.

Department of Chemistry. University of KalyaniKalyani-741 285 Government Quinine Factory, Mangpoo, Darjeeling Manuscript received 29 April 1988, revised 10 August 1988,accepted 17 August 1988 Chemical Constituents of Nephrolepis tuberosa.

Department of Physical Chemistry, India.n Association for the Cultivation of Science, Jadavpur, Calcutta.-700 032 Manuscript received 14 May 1980, revised 14 July 1981, accepted 26 February1989 Polyethylene, though quite insoluble in any single solvent at near room temperatare was earlier found to dissolve in a mixture of two non-solvents. A few such co- solvent pairs, including some new ones, have been studied in details with respect to cloud temperature and the existence of optimum solvent composition as judged by a maximum in intrinsic viscosity. The failure of Gee's criterion for cosolvency has been pointed out. The results have also been discussed, with only partial success, with respect to an equation derived by Deb and Palit, based on the thermodynamic approach of Scott. Probably, some kind of specific interaction and structure formation play an important role in such cosolvency.

The reactions of methyl-substituted chlorocyclotriphosphazenes with aryl Grignard reagents and with bifunctional amines, aminoalcohols, and alkoxides were investigated. The characterization data for the compounds formed in the reactions of monomethylpentachlorocyclotriphosphazene and the Grignard reagents were found to be informative with respect to the extent and nature of the interaction between the phosphazene ring and its exocyclic substituents. This interaction was found to be responsible for significant effects on the reactions of the phosphazene ring with nucleophiles. The reactions of the bifunctional nucleophiles were found to be useful probes of the reactivity of the phosphazene ring. Specifically, a single methyl group is found to activate the chlorine on the same phosphorus atom, while a pair of geminally substituted methyl groups is found to deactivate the chlorine atoms on a different phosphorus atom. The results allow a new interpretation of the substitution patterns of various nucleophiles on chlorocyclotriphosphazenes. Ph. D. incomplete_metadata

Several 5-methyl-5-substituted benzyl barbiturates and thiobarbiturates as well as the substituted benzyl malonic esters required for the synthesis of above compounds have been prepared and described.

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Earlier researches on the transformations of terpineol with fused potassium hydrogen sulphate, aq. oxalic acid, sulphuric-acetic acid mixture and \(\gamma\)-alumina have been repeated, and in the reaction mixtures, α-terpinene, limonene and saturates have been quantitatively estimated. Reactions of terpineol, catalysed by iodine and boric acid, have been examined, and iodine has been found to be an excellent and quick agent for dehydrating terpineol. For eliminating α-terpinene in terpene mixtures, warming with maleic anhydride is shown to be a better route than agitating with cold Beckmann's chromic acid mixture. Bromination of terpinolene by Baeyer's technique has been improved, the essential change being the precipitation of the tetrabromide by addition of cold methanol. This modification avoids the Formation of oily products. No clean-cut elimination path for terpineol is revealed excepting in dehydrations with potassium hydrogen sulphate and alumina, wherein dl-limonene and terpinolene respectively are obtained as major reaction products. In all other cases, there result monocyclics containing α-terpinene, terpinolene, limonene and saturates including p-cymene, in varying proportions. A mechanism is proposed to account for the reaction products and to explain how terpineol can furnish both terpi­nolene and limonene with equal facility.

Some Aspects of Biochemical Synthesis.

Chemical Constituents of \(Centipeda\) \(minima.\)

The syntheses of 1 : 3 : 5-triketones, namely αα'-diformylacetone dicarboxylic ester and αα'-diformylacetone have been described.

The following substances have been studied for their chemical activity as expressed by the velocity of replace­ment of the chlorine atom in them (1) Monochlormalondiphenylamide (2) Monochlormalondi-p-tolylamide. (3) Monochlormalondi-o-tolylamide. (4) Nionochlormalondi-1:3:4-xylylamide. The results indicate that the following factors influence the velocity of replacement of the chlorine atom by hydrogen : (i) The positions of the radicals like the methyl groups in the nuclear rings attached to the carbonyl groups, (ii) The molecular weights of the residues carried by the carbonyl groups, (iii) The nature of the nuclei attached to the carbonyl groups between which the carbon atom carrying the chlorine atom is situated.

Studies in the Cotarnine Series. Part I. Action of Phenyl isoCyanate and Phenyl isoThiocyanate on Cotarnine.