Enzymatic production of dihydroxyacetone (DHA) was studied by immobilization of the whole cells of acetic acid bacteria capable of oxidizing glycerol to DHA. Acetobacter xylinum A-9 cells immobilized in a polyacrylamide gel were selected as the most favorable enzyme preparation. The enzymatic properties of immobilized cells converting glycerol to DHA were investigated and compared with those of...

We present the first report of enzymatic catalysis in an ionic liquid. The virtually nonexistent vapor pressure makes ionic liquids an exciting new alternative for enzyme-catalyzed syntheses in environmentally friendly environments. Z-aspartame was synthesized in a thermolysin-catalyzed reaction of carbobenzoxy-L-aspartate and L-phenylalanine methyl ester hydrochloride in 1-butyl-3-methylimidaz...

Biosensors have been developed for the detection of pesticides using integrated enzymes, antibodies, cell and DNA-based biosensors. Enzymatic determination of pesticides is most often based on inhibition of the activity of selected enzymes such as cholinesterase, acid phosphatase, ascorbate oxidase, acetolactate synthase and aldehyde dehydrogenase. Enzymatic Biosensors were developed using vari...

OBJECTIVES (S)-Mandelate dehydrogenase (SMDH) and laccase were immobilized on chitosan. The bi-enzymatic system with immobilized SMDH and immobilized laccase was taken to catalyze the stereoselective transformation of racemic mandelic acid and (R)-mandelic acid was obtained from its racemic mixture. RESULTS Characteristics of the immobilized enzymes were valuated. The optimum pH and temperatu...

Production of optically pure products can be based on simple unselective synthesis of racemic mixtures combined with a subsequent separation of the enantiomers. However, this approach suffers from a 50% yield limitation which can be overcome by racemization of the undesired enantiomer and recycling. Application of biocatalyst for the racemization steps offers an attractive option for high-yield...

In recent years the usefulness of enzymatic systems to obtain a single stereoisomerically pure compound starting from a racemate has been expanded. Moreover, current advances in protein engineering, molecular biology and modeling tools are the basis to improve the catalytic properties of enzymes to face novel synthetic challenges. Also, medium engineering and novel immobilization methods of (bi...

Two microbial lipases from Burkholderia cepacia and Pseudomonas fluorescens were evaluated as catalysts for the enzymatic transesterification of beef tallow with ethanol and the most efficient lipase source was selected by taking into account the properties of the product to be used as fuel. Both lipases were immobilized on an epoxy silica-polyvinyl alcohol composite by covalent immobilization ...

A photo-electrochemical sensor for the specific detection of guanosine monophosphate (GMP) is demonstrated, based on three enzymes combined in a coupled reaction assay. The first reaction involves the adenosine triphosphate (ATP)-dependent conversion of GMP to guanosine diphosphate (GDP) by guanylate kinase, which warrants substrate specificity. The reaction products ADP and GDPare co-substrate...

Structured lipids (SL) are defined as triacylglycerols (TAG) restructured or modified to change the fatty acid composition and/or their positional distribution in glycerol molecules by chemical or enzymatic processes. SL may provide the most effective means of delivering desired fatty acids for nutritive or therapeutic purposes. In this review, the synthesis and applications of structured lipid...