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We have developed an easy and flexible synthetic methodology to obtain lipid chains containing methanothiosulfonate terminal groups with the aim to attach them to natural proteins as functional groups. There are many proteins found in nature that are modified by lipids, and this is a key part of their function. For example, the prion protein is attached to the plasma membrane via a glycosylphosphatidylinositol (GPI) anchor, and this protein is thought to be the causative agent in diseases such as bovine spongiform encephalopathy (BSE; “mad cow disease”) and the human equivalent Creutzfeldt–Jakob disease. However, production of large amounts of protein in bacteria results in proteins that lack these lipid modifications. The lipid chains containing methanothiosulfonate terminal groups that we have synthesized here can be attached to these proteins through the thiol contained in the side chain of the cysteine residue, which can be incorporated into the protein sequence at the desired position.

A systematic solid-state 17O NMR study of a series of carboxylic compounds, maleic acid, chloromaleic acid, KH maleate, KH chloromaleate, K2 chloromaleate, and LiH phthalate.MeOH, is reported. Magic-angle spinning (MAS), triple-quantum (3Q) MAS, and double angle rotation (DOR) 17O NMR spectra were recorded at high magnetic fields (14.1 and 18.8 T). 17O MAS NMR for metal-free carboxylic acids and metal-containing carboxylic salts show featured spectra and demonstrate that this combined, where necessary, with DOR and 3QMAS, can yield site-specific information for samples containing multiple oxygen sites. In addition to 17O NMR spectroscopy, extensive quantum mechanical calculations were carried out to explore the influence of hydrogen bonding at these oxygen sites. B3LYP/6-311G++(d,p) calculations of 17O NMR parameters yielded good agreement with the experimental values. Linear correlations are observed between the calculated 17O NMR parameters and the hydrogen bond strengths, suggesting the possibility of estimating H-bonding information from 17O NMR data. The calculations also revealed intermolecular H-bond effects on the 17O NMR shielding tensors. It is found that the delta11 and delta22 components of the chemical shift tensor at O-H and C=O, respectively, are aligned nearly parallel with the strong H-bond and shift away from this direction as the H-bond interaction weakens.

The potential of surface glycoengineering for biomaterials and biosensors originates from the importance of carbohydrate–protein interactions in biological systems. The strategy employed here utilises carbene generated by illumination of diazirine to achieve covalent bonding of carbohydrates. Here, we describe the synthesis of an aryl diazirine containing a disaccharide (lactose). Surface analysis techniques [X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToF-SIMS)] demonstrate its successful surface immobilisation on polystyrene (PS). Results are compared to those previously obtained with an aryl diazirine containing a monosaccharide (galactose). The biological activity of galactose- or lactose-modified PS samples is studied using rat hepatocytes, Allo A lectin and solid-phase semi-synthesis with α-2,6-sialyltransferase. Allo A shows some binding to galactose-modified PS but none to lactose-modified surfaces. Similar results are obtained with rat hepatocytes. In contrast, sialylation of lactose-modified PS is achieved but not with galactose-modified surfaces. The different responses indicate that the biological activity depends not only on the carbohydrate per se but also on the structure and length of the spacer.

Elucidating the stereoselectivity of lipases in synthetic reactions of triacylglycerols has hitherto been carried out using traditional analytical techniques to determine the composition of the reaction products. These methods are laborious and are not always appropriate for analysis of certain triacylglycerol types. A direct method, utilizing a stereospecific deuterium-labeled triacylglycerol substrate, has been developed where the stereoisomeric composition of the reaction product is determined by ultra-high resolution 13C nuclear magnetic resonance (NMR) spectroscopy. Through lipase-catalyzed transesterification of deuterium-labeled trilauroylglycerol with oleic acid, chemical shifts were induced in the 13C NMR spectrum by the deuterium atom and olefinic double bonds, enabling unambiguous stereospecific assignment of triacylglycerol species. By this method of analysis, we found an effect of the degree of reaction conversion on the extent of stereoisomerism in the triacylglycerol product. Stereoselectivity was greatest (for sn-1) with lipase from Rhizomucor miehei. Lipases from Rhizopus niveus, Candida rugosa, Carica papaya, and the cutinase from Fusarium sp. were also found to exhibit stereoselectivity, with preference for either sn-1 or sn-3 acyl exchange.

Time-of-flight Secondary Ion Mass Spectrometry (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS) are used to characterize a newly synthesized glycosylated photoactivatable reagent designed for surface glycoengineering. The immobilization on diamond surfaces of the glycoaryldiazirine reagent lactose aryl diazirine (5-carboxamidopentyl-N-[m-[3-(trifluoromethyl)diazirin-3-yl]phenyl-β-D-galactopyranosyl]-(1->4)-1-thio-β-D-glucopyranoside) is compared to a previously studied monoglycosylated photoactivatable reagent (MAD-Gal). The XPS atomic constituents and chemical shifts, as well as ToF-SIMS specific characteristic fragments and molecular peaks of the new photoimmobilized molecule are recorded. Spectral differences are identified in XPS C 1s spectra and in the high mass range of positive ion ToF-SIMS spectra for the surface immobilized disaccharide. The ToF-SIMS characteristic high-mass ions involve both cationization with Na+ and loss of the diazirine function. The results can be related to differences observed in biological assays with each of the surface immobilized saccharides. Copyright © 2001 John Wiley & Sons, Ltd.

Immobilisation of the β-galactosidase of Bacillus circulans on Eupergit C gave a highly selective and stable biocatalyst. The immobilised enzyme catalysed the transfer of the β-galactosyl residue of p-nitrophenyl β- d -galactopyranoside to N-acetylglucosamine with high selectivity for transfer to the 4-position of the glycosyl acceptor.

Two synthetically useful glycosidases, the beta-galactosidase from Bacillus circulans and an alpha-galactosidase from Aspergillus oryzae have been immobilized on Eupergit C. The immobilized enzymes retain high catalytic activity and show increased thermal stability compared with the free enzymes.

An α-galactosidase capable of α-galactosyl transfer on to a 4-position of sugar acceptors was isolated from Aspergillus niger and purified to homogeneity. The enzyme was characterised with respect to its pH and temperature optima and stability, molecular mass and pI. Inhibition by compounds relevant to a potential application of the enzyme for oligosaccharide synthesis was investigated.

Tritiated glyoxylic acid was incubated with pyruvate decarboxylase. The hydroxymethylthiamine diphosphate formed was ozonolysed to give tritiated glycolic acid, the absolute configuration of which was investigated by analysis using glycolate oxidase. The tritiated glycolic acid proved to be racemic. The implications of this result are discussed in relation to models for the mechanism of pyruvate decarboxylase.

Two disaccharides, α- d -Man p -(1→2)- d -Man p 6 and α- d -Man p -(1→3)- d -Man p 7 , were synthesised from mannose using the reverse hydrolysis activity of the partially purified α-mannosidases from almond ( Prunus amygdalus ) meal and limpets ( Patella vulgata ). Both disaccharides were isolated by carbon–Celite chromatography. Attempts were also made towards the synthesis of core pentasaccharide using the purified α-mannosidase from Aspergillus niger .

Oligosaccharides containing a β-N-acetylglucosamine moiety are useful building blocks for the synthesis of complex substances with important functions in vivo, such as cell recognition, adhesion, and communication. Microbial β-N-acetylhexosaminidases have been applied to the preparation of a wide range of such biologically significant compounds. In addition, they have been employed for the analysis of complex sugar chains in glycoproteins and glycopeptides, and they have found application as biocontrol agents, particularly against fungal pathogens of plants. This survey compares amino acid sequence data, biochemical characteristics, and catalytic properties of β-N-acetylhexosaminidases from a number of microbial sources.

Glycosidases were used to prepare oligosaccharide structures of physiological and medicinal relevance. The study included an extensive screening of crude enzymatic preparations for α- and β-galactosidase, α- and β-mannosidase, β-N-acetylglucosaminidase, β-N-acetylgalactosaminidase and α- l -fucosidase activities. The enzymes were assessed with respect to regioselectivity of glycosyl transfer on to carbohydrate acceptors. The purification procedures for individual biocatalysts are described in detail.

The β-N-acetylhexosaminidase from Aspergillus oryzae and the β-mannosidases from Helix pomatia and A. oryzae were purified and used to synthesise the core trisaccharide of N-linked glycoproteins, Manp-(1→4)-β-D-GlcpNAc-(1→4)-D-GlcpNAc.

Pig liver esterase-catalysed hydrolysis of (±)-endo-2-methoxycarbonyl-7-oxabicyclo[2.2.1]hept-5-ene 1a provides (–)-endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carboxylic acid 1b and (+)-endo-2-methoxycarbonyl-7-oxabicyclo[2.2.1]hept-5-ene 1a in 36 and 57% ee, respectively. Transesterification between (±)-2-exo-hydroxy-4,8-dioxatricyclo[4.2.1.03,7]nonan-5-one 2a and vinyl acetate catalysed by the lipase from Pseudomonas fragi gives the acetate (–)-2b and alcohol (+)-2a in 91 and 94% ee, respectively. Optically pure acetate (–)-2b is obtained after removal of contaminating racemate from the impure acetate by crystallisation of (–)-2b of 91% ee (EtOH).

N-Acetyllactosamine 5 is obtained by transglycoslyation between p-nitrophenyl β-D-galactopyranoside 3 and N-acetyl-D-glucosamine 4 by using the β-galactosidase from Bacillus circulans as the biocatalyst. Sodium salts of β-Gal(6-SO4)-(1→4)-GlcNAc 1 and β-Gal-(1→4)-GlcNAc(6-SO4) 2 have been prepared from N-acetyllactosamine 5 in five and three steps respectively. β-D-GlcNAc-(1→4)-D-GlcNAc(6-SO4) (di-N-acetylchitobiose 6-sulfate) 10 is synthesised from chitin in three steps. The products have been tested as fucosyl acceptors in reactions catalysed by recombinant human fucosyltransferases III to VII.

The esterase from Rhodosporidium toruloides has been used to catalyse the hydrolysis of a series of per-acetylated α-D-hexopyranoses and α-D-hexopyranosides. Per-acetylated glucose 4, mannose 6, N-acetylgalactosamine 8, galactose 10, methyl α-D-glucoside 12, methyl α-D-mannoside 14 and methyl α-D-galactoside 16 have been selectively cleaved at the C-6 position by the esterase to give the 6-OH derivatives 5, 7, 9, 11, 13, 15 and 17. Acid-catalysed rearrangement of acetates 5, 7, 13, 15, 11, 17 and 9 with 4→6 acetyl migration gives the corresponding 4-deprotected derivatives 22–28, respectively. Hydrolyses of β-D-glucose pentaacetate 20 and α-D-lactose octaacetate 21 have been attempted, but no hydrolyses have been observed. 1,2,3,6-Tetraacylated α-D-hexopyranoses 3 and 22, derivatives of N-acetylglucosamine and glucose respectively, and 2,3,6-triacetylated α-D-hexopyranosides 24 and 25, derivatives of glucose and mannose, respectively, have been hydrolysed by the esterase to the corresponding 4,6-dihydroxy acetates 29, 18, 30 and 31. Acylation of methyl α-D-glucopyranoside 32 catalysed by the esterase provides the C-6 monoacetate 33 and the C-3 monoacetate 34 in 4 and 5% yield, respectively. The sodium salts of N-acetylglucosamine, glucose, N-acetylgalactosamine, galactose and mannose 6-sulfates 38–42, respectively, are prepared in two steps from the 6-deacetylated hexopyranoses 2, 5, 9, 11 and 7, respectively. The sodium salts of N-acetylglucosamine, glucose and mannose 4-sulfates 43–45, respectively, are prepared in two steps from the 4-deacetylated precursors 3, 22 and 26 which are obtained via acid catalysed 4→6 acyl migration of compounds 2, 5 and 7.

Globotriose [α-D-Gal-(1→4)-β-D-Gal-(1→4)-D-Glc] is the carbohydrate moiety of the globotriosyl ceramide (Gb3), also known as the germinal centre B-cell differentiation antigen CD77, a glycolipid present on the plasma membrane of certain mammalian cells. In Gb3, globotriose functions as the cell-surface receptor for Shiga toxin and for the Shiga-like toxins (verocytotoxins). Here we report the chemical synthesis of globotriose and the corresponding terminal disaccharide, galabiose [α-D-Gal-(1→4)-β-D-Gal]. Globotriose and galabiose are attached via a linker to CNBr-activated Sepharose to generate affinity matrices that permit the one-step purification of recombinant Shiga-like toxin-1 from crude E. coli homogenates. Toxin is released from either of the immobilised saccharides by elution with 6 M guanidinium chloride. After dilution of the denaturant, the released toxin had full catalytic activity. Denaturation-titration experiments show that the bound toxin is released from galabiose-Sepharose at 2.3 M guanidinium chloride, while its release from globotriose-Sepharose requires a higher concentration of 4.8 M. These results indicate that the glucose component of globotriose contributes ≈2.6 kcal mol–1 to the binding energy relative to galabiose.

Almond β- d -glucosidase was used to catalyze alkyl-β- d -glucoside synthesis by reacting glucose and the alcohol in organic media. The influence of five different solvents and the thermodynamic water activity on the reaction have been studied. The best yields were obtained in 80 or 90% (v/v) tert-butanol, acetone, or acetonitrile where the enzyme is very stable. In this enzymatic synthesis under thermodynamic control, the yield increases as the water activity of the reaction medium decreases. Enzymatic preparative-scale syntheses were performed in a tert-butanol-water mixture which was found to be the most appropriate medium. 2-Hydroxybenzyl β- d -glucopyranoside was obtained in 17% yield using a 90:10 (v/v) tert-butanol-water mixture. Octyl-β-glucopyranoside was obtained in 8% yield using a 60:30:10 (v/v) tert-butanol-octanol-water mixture.

Pseudo-α-L-fucopyranose 1 and pseudo-6-deoxy-β-D-altropyranose 2 have been synthesised from ((5 S ,6 R )-5,6-dihydroxy-1,3-cyclohexadienyl)methanenitrile 3 .

β-Galactosidase from Aspergillus oryzae, α-galactosidase from Aspergillus niger, β-mannosidase from Helix pomatia and β-glucosidase from almond were used to synthesise different glycosides by reverse hydrolysis: GlcβO(CH2)6OH 1 was obtained in 61% yield, β-D-Glc-O(CH2)3CH-CH2 2 in 50% yield, β-D-Glc-O(CH2)2Si(Me)3 3 in 11% yield, β-D-Gal-O(CH2)6OH 4 in 48% yield, β-D-Gal-O(CH2)3CH-CH2 5 in 22% yield, α-D-Gal-O(CH2)6OH 6 in 47% yield, α-D-GalO(CH2)3CH-CH2 7 in 37% yield and β-D-ManO(CH2)6OH 8 in 12% yield. Using the appropriate glycosides methyl O-(2,3,4,6-tetra-O-benzyl-α-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzoyl-1-O-α-D-galactopyranoside 11 and 6′-benzoylhexyl-O-(2,3,4,6-tetra-O-benzyl-α-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzoyl-1-O-β-D-galactopyranoside 15 were synthesised. This chemoenzymatic approach avoided at least four chemical steps that would have been necessary in a conventional synthesis.

Different ethyl 1-thio-β-D-disaccharides have been synthesised by transgalactosylation using the β-galactosidase from Bacillus circulans as biocatalyst. This β-galactosidase shows mainly a β-1–4 specificity in the galactosyl transfer. Gal-β-(1–4)-O-β-D-GlcSEt 15 was obtained in 36% yield, Gal-β-(1ndash;4)-O-α-D-GlcSEt 19 in 30% yield, Gal-β-(1–4)-O-β-D-GalSEt 17 in 60% yield, Gal-β-(1–4)-O-β-D-GalNAcSEt 20 in 49% yield, Gal-β-(1–4)-O-β-D-Gal-β-(1–4)-O-β-D-GalNAcSEt 21 in 9% yield, Gal-β-(1–6)-O-β-D-GlcSEt 16 in 3% yield and Gal-β-(1–3)-O-β-D-XylSEt 18 in 25% yield.

A six step synthesis of (−)-6-hydroxyshikimic acid 2 has been developed starting from ((5S, 6R)-5,6-dihydroxy-1,3-cyclohexadienyl)methanenitrile 3 , produced by biotransformation of cyanobenzene by the enzyme toluene dioxygenase.

Using crystal structure data for the pyruvate decarboxylase from Saccharomyces uvarum (which is nearly identical with the enzyme from Saccharomyces cerevisiae), molecular modeling studies have been carried out to investigate the mode of action of the enzyme. Each step of the decarboxylation mechanism can be explained by assuming that the 4‘-amino group of thiamin diphosphate (TDP) acts as a general acid and, in its deprotonated form, as a general base. The carboxyl group of Glu 477 plays a key role in both pyruvate decarboxylation and acyloin formation. In the first case it interacts with the carboxylate group of pyruvate to stabilize the incipient dianion formed by attack of the thiazolium carbanion on pyruvate. In the second case, it interacts with the developing alkoxide anion arising from attack on acetaldehyde or benzaldehyde by the carbanion−enamine intermediate. These studies have permitted the assignment of configuration to all of the key intermediates in the catalytic process. Thus the carbanion−...

Pyruvate decarboxylase from Saccharomyces cerevisiae catalyses the formation of lactaldehyde from sodium glyoxylate and acetaldehyde. By using deuteriated sodium glyoxylate (sodium [2-2H]glyoxylate monohydrate) as a substrate it was verified that the lactaldehyde formed retains the deuterium atom. The implications of the observed result for the enzyme mechanism are discussed in the light of conclusions derived from recent molecular modelling studies.

The N-acetylhexosaminidase from Aspergillus oryzae catalyse transfer of N-acetylglucosaminyl and N-acetylgalactosaminyl residues selectively on to the 6-OH group of N-acetylgalactosamine to give the corresponding (1→6)-linked disaccharides 3 and 6 in 26 and 38% yield, respectively. The disaccharide β-D-GlcpNAc-(1→6)-β-D-GalpNAc 3 thus synthesized acts as acceptor for transfer of a β-D-galactosyl residue from the corresponding p-nitrophenyl glycoside on to the 4-OH group of the non-reducing unit to give the ovarian cyst fluid mucin fragment β-D-Galp-(1→4)-β-GlcpNAc-(1→6)-D-GalpNAc 8 in 48% yield together with the tetrasaccharide β-D-Galp-(1→4)-β-D-Gal-(1→4)-β-D-GlcpNAc-(1→6)-D-GalpNAc 9 in 7% yield. With lactose as acceptor, the trisaccharide β-D-Galp-(1→4)-β-D-Galp-(1→4)-D-Glcp 12, a growth factor for human intestinal bifidobacteria, is produced in 52% yield.p

Using a crude β-N-acetylhexosaminidase from Aspergillus oryzae both tri-N-acetylchitotriose (GlcNAc)3 (1, n=1) and tetra-N-acetylchitotetraose (GlcNAc)4 (1, n=2) act respectively as both glycosyl donor and glycosyl acceptor to give product mixtures containing significant quantities of the corresponding penta- and hexasaccharides [1 (n=3) and 1 (n=4), respectively] which are readily isolated and purified by charcoal-Celite chromatography.

The reduction of αβ-unsaturated ketones with γ-sulfide, sulfoxide, sulfone, nitrile and ester functions has been investigated. Both CO and CC reduction was observed. In the sulfur series, CO bond reduction was always observed, but significant CC bond reduction was observed only with the sulfide. The unsaturated nitriles gave the corresponding alcohol as the major bioreduction product, with smaller but significant amounts of fully reduced product. A similar result was obtained with the ester substrate. Relative and absolute configurations of bioreduction products were determined. A comparison was made between reductions catalysed by bakers' yeast (Saccharomyces cerevisiae) and by other yeasts (Zygosaccharomyces rouxii, Pichia capsulata, P. farinosa, Candida chalmersi and C. diddensiae). The tendency of Z. rouxii to give products enantiomeric with those obtained using S. cerevisiae was noted. The relationship between substrate structure and the stereochemistry of CC double bond reduction is discussed.

Zygosaccharomyces rouxii catalysed the reduction of ethyl 4-chloroacetoacetate (ethyl 4-chloro-3-oxobutanoate) to the corresponding (S)-hydroxy ester (ethyl (S)-4-chloro-3-hydroxybutanoate) in high enantiomeric excess. The productivity of non-immobilised cells was compared to cells immobilised on a range of organic and inorganic supports. Cells immobilised in calcium alginate displayed a catalytic activity significantly higher than that of non-immobilised cells. A time dependent fall in the enantiomeric purity of the product was observed with the use of this matrix. This phenomenon was not seen in the reduction catalysed by non-immobilised cells.

Six yeasts were studied for their ability to reduce ethyl 4-chloroacetoacetate (ethyl 4-chloro-3-oxobutanoate) stereoselectively. Five species reduced the substrate to ethyl (S)-4-chloro-3-hydroxybutanoate of high (92–99%) optical purity. With glucose-grown cells, substrate reduction could only be demonstrated when growth was oxygen-limited, whereas xylose-grown Pichia capsulata could be grown under conditions of oxygen excess without losing its reducing ability. Zygosaccha-romyces rouxii exhibited high enantioselectivity (≥98% ee (S)-enantiomer) under all conditions tested, whilst in P. capsulata, a novel switch was observed from producing mainly the (R)-enantiomer using glucose as co-substrate to producing mainly the (R)-enantiomer using 2-propanol as co-substrate. This switch was correlated with a change in reduction predominantly from an NADPH-dependent dehydrogenase system to an NADH-dependent system. In the production of ethyl (R)-4-chloro-3-hydroxybutanoate with P. capsulata, the enantioselectivity...

Glucosidase-catalysed synthesis of glucosides with a spacer arm on the anomeric carbon is reported. By using the acceptor as solvent at an elevated temperature, much higher yields of product have been obtained than previously observed.

The effect of surfactants on the hydrolysis of prochiral and chiral substrates by crude and purified porcine pancreatic lipase (PPL, EC 3.1.1.3)) has been studied. Rather than accelerating the reactions, surfactants slowed down (“inhibited”) the reactions relative to the rate in the absence of surfactant. Surfactants varied in the extent to which the reaction was inhibited. With the crude enzyme there was a correlation between degree of inhibition and the optical purity of the product of hydrolysis of an achiral diester substrate 1. There was no special effect associated with use of surfactants in the concentration range corresponding to critical micelle formation, nor was there any increase in rate of reaction when stable emulsions were formed by using mixtures of surfactants to generate an appropriate hydrophile-lipophile (HLB) balance. A study of the effect of sodium dodecyl sulphate (SDS) on the hydrolysis of the diester 1 by crude PPL showed that the rate of the reaction steadily decreased with incre...

α-Chymotrypsin suspended in organic solvents with low water content catalysed hydrolytic reactions in the presence of ammonium hydrogen carbonate. Molecular modelling studies were carried out and structure–reactivity relationships were established by studying the hydrolysis of amino acid derivatives and analogues. The enzyme was found to be stereoselective with respect to the hydrolysis of L-amino acid derivatives, but no stereoselectivity was observed when α-hydroxy esters were used as substrates. A general procedure for the resolution of aromatic amino acid esters is given. The results are interpreted in terms of molecular modelling based on X-ray crystallographic data and literature data.

Pseudo-α-L-fucopyranose 1 and pseudo-6-deoxy-β-D-altropyranose 2 have been synthesised from ((5 S ,6 R )-5,6-dihydroxy-1,3-cyclohexadienyl)methanenitrile 3 .

The stereochemistry of the alkali-catalysed rearrangement of α-acetohydroxybutyrate (2-ethyl-2-hydroxy-3-oxobutanoate) was studied. The rearrangement was found to proceed via a transition state in which a syn arrangement of the C–O bonds is preferred over the anti arrangement by a factor of ≥2:1.

Pyruvate decarboxylase from Saccharomyces sp. catalysed the formation of acetoin of predominantly the opposite configuration than that obtained using the enzyme from Zymomonas mobilis. A similar result was obtained for the lactaldehyde formed in the pyruvate decarboxylase-catalysed decarboxylation of glyoxylate in the presence of acetaldehyde. The results are interpreted in terms of different Boltzmann distributions for the two enzymes between the enzyme–substrate complexes of acetaldehyde bound on its re and si faces respectively.

Dimethyl cis -2-cyclobutene-1,2-dicarboxylate 1 was kinetically resolved by porcine liver esterase to give methyl hydrogen (1 R , 2 S )- (+)- cis -3-cyclobutene-1,2-dicarboxylate 3 . ((1 R ,4 S )-4-Ethanoyloxymethyl-2-cyclobutenyl)methyl ethanoate 2 was kinetically resolved using the lipase from Pseudomonas fluorescens (Amano P) to give ((1 R ,4 S )-4-hydroxymethyl-2-cyclobutenyl)methyl ethanoate 8 .

A three-step synthesis of vinylglycine 1 has been developed using a readily available starting material (but-3-enenitrile 2), based on the Neber rearrangement of the corresponding N-chloroimidate, and using cheap, convenient reagents. Also described is a convenient optical resolution of the N-tert-butoxycarbonyl derivative by papain-catalysed enantioselective esterification in a two-phase system. From the optically active amino acid, related amino acids obtained via epoxidation, dihydroxylation and cyclopropanation have been prepared. The related β, γ-unsaturated amino acids (E)-2-aminopent-3-enoic acid 20 and (E)-2-amino-3-methylpent-3-enoic acid 22 have been synthesised using the same approach.

(1R, 2R, 3S, 4S)-1-Hydroxymethylcyclopentane-2,3,4-trio 2, a possible precursor of aristeromycin 1 was synthesised in tritiated form and administered to Streptomyces citricolor. Radioactivity was incorporated into aristeromycin, but degradation showed that incorporation of radioactivity was nonspecific, indicating that the tetrol 2 is not an immediate precursor of aristeromycin 1.

A six step synthesis of (−)-6-hydroxyshikimic acid 2 has been developed starting from ((5S, 6R)-5,6-dihydroxy-1,3-cyclohexadienyl)methanenitrile 3 , produced by biotransformation of cyanobenzene by the enzyme toluene dioxygenase.

Recombinant pyruvate decarboxylase from Zymomonas mobilis catalysed the formation of R-aromatic acyloins of high optical purity from aromatic aldehydes and either pyruvate or acetaldehyde. The results are contrasted with those obtained with aliphatic acyloins and compared with those obtained with the pyruvate decarboxylase of Saccharomyces sp.

Octyl oxalamic esters of 1-phenylethylamine and substituted 1-phenylethylamines are kinetically resolved with high stereoselectivity by lipase B from Candida antarctica.

Remarkable advances in glycobiology in recent years have stimulated a resurgence of interest in carbohydrate chemistry. The challenge of producing the complex glycosides and oligosaccharides needed for research in glycobiology has led to the development of enzymatic methods that are now firmly established as part of the synthetic repertoire of the carbohydrate chemist.

Pig liver esterase-catalysed hydrolysis of (±)-endo-2-methoxycarbonyl-7-oxabicyclo[2.2.1]hept-5-ene 1a provides (–)-endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carboxylic acid 1b and (+)-endo-2-methoxycarbonyl-7-oxabicyclo[2.2.1]hept-5-ene 1a in 36 and 57% ee, respectively. Transesterification between (±)-2-exo-hydroxy-4,8-dioxatricyclo[4.2.1.03,7]nonan-5-one 2a and vinyl acetate catalysed by the lipase from Pseudomonas fragi gives the acetate (–)-2b and alcohol (+)-2a in 91 and 94% ee, respectively. Optically pure acetate (–)-2b is obtained after removal of contaminating racemate from the impure acetate by crystallisation of (–)-2b of 91% ee (EtOH).

The β-N-acetylhexosaminidase from Aspergillus oryzae and the β-mannosidases from Helix pomatia and A. oryzae were purified and used to synthesise the core trisaccharide of N-linked glycoproteins, Manp-(1→4)-β-D-GlcpNAc-(1→4)-D-GlcpNAc.

A novel chiral stationary phase consisting of poly-L-leucine supported on porous graphitic carbon has been shown to be effective in the separation of the enantiomers of epoxides 1-5 by chiral high performance liquid chromatography.

The kinetic resolution of a precursor of the dihydropyridine UK-74,505, 1 , an antagonist of platelet activating factor, is described, in which rabbit liver esterase was used to catalyse the hydrolysis of an ester function linked to the chiral centre via a spacer arm of appropriate length.

The hydrolysis of a prochiral diacetate by porcine pancreatic lipase is catalysed by the purified enzyme, not by an enzyme present in the crude enzyme but absent from the purified enzyme, as previously reported.