Abstract: The present invention relates to an optically active .alpha.-substituted carboxylic acid derivative represented by the general formula (I): ##STR1## (wherein R.sub.1 is a hydroxyl group, ##STR2## R.sub.2 is a methyl group or a chlorine atom; R.sub.3 is a hydrogen atom or an alkyl group with 1-6 carbon atoms; n is an integer of 1 or 2; and * represents an asymmetric carbon atom, provided that R.sub.2 is a chlorine atom when R.sub.1 is a hydroxyl group);and a method for producing the optically active .alpha.-substituted carboxylic acid derivative represented by the general formula (I) and antipodes thereof using a culture, cells or a material obtainable from cells of a microorganism having an ability to asymmetrically hydrolyze ester bonds. The optically active .alpha.-substituted carboxylic acid derivatives and antipodes thereof provided by the invention are useful as raw materials for various liquid crystals and as synthetic intermediates for various optically active medicines or agricultural chemicals.

Abstract: The present invention relates to a process for producing D-lactic acid and L-lactamide, comprising allowing a culture broth of a microorganism capable of asymmetric hydrolysis of DL-lactamide belonging to the genus Alcaligenes, Pseudomonas, Agrobacterium, Brevibacterium, Acinetobacter, Corynebacterium, Enterobacter, Micrococcus or Rhodococcus, the microorganism itself, a material obtained therefrom or an immobilized material thereof to act on DL-lactamide, and recovering the resulting D-lactic acid and the remaining L-lactamide. The present invention enables sufficient production of D-lactic acid and L-lactamide by the present microorganism.

Abstract: The present invention relates to a DNA fragment containing a nucleotide sequence that encodes an amino acid sequence of esterase, said esterase asymmetrically hydrolyzing carboxylic acid esters represented by the formula (I); ##STR1## (wherein R.sub.1 is alkyl, aralkyl or aryl, R.sub.2 and R.sub.3 are alkyl, and n is 1 or 2) an esterase encoded by the DNA fragment, a recombinant plasmid containing the DNA fragment, a microorganism transformed with the recombinant plasmid and methods of producing optically active carboxylic acids and their enantiomeric esters.

Abstract: N-(3-acetylthio-2-D-methylpropionyl)-L-proline useful as a precursor of captopril, one of antihypertensive agents, is prepared by allowing thioacetic acid to react with methyl methacrylate to prepare racetalc methyl 3-acetylthio-2-DL-methylpropionate, contacting the propionate with cells of, for example, Pseudomonas in order to effect biological and asymmetric hydrolysis, extracting 3-acetylthio-D-2-methylpropionic acid and allowing the acid to react with L-proline.

Abstract: An L-proline derivative represented by: ##STR1## wherein R.sub.2 represents a lower alkyl group is prepared by reacting L-proline with a D-.alpha.-alkyl-.beta.-acylthiopropionic acid halide, ##STR2## wherein R.sub.1 represents an acyl group, X represents a halogen atom and R.sub.2 has the same meaning as defined above. The halide is added to an aqueous medium containing L-proline and a condensation agent for deacidification. The halide and L-proline are reacted while the reaction temperature and pH are maintained at 12.degree. C. or lower and within a range of 10.5-11.5, whereby a compound represented by: ##STR3## wherein R.sub.1 and R.sub.2 have the same meanings as defined above is obtained. The resulting compound is then subjected to deacylation under strong alkaline conditions without being isolated from the reaction mixture, thereby yielding the target L-proline derivative.

Abstract: An organic acid ester of ascorbic acid or erythorbic acid is produced by reacting ascorbic acid or erythorbic acid with an organic acid enol ester in an organic solvent with a solubility of ascorbic acid or erythorbic acid of more than 0.3% at 25.degree. C. in the presence of an active lipase.

Abstract: The present invention relates to a DNA fragment containing a nucleotide sequence that encodes an amino acid sequence of esterase, said esterase asymmetrically hydrolyzing carboxylic acid esters represented by the formula (I); ##STR1## (wherein R.sub.1 is alkyl, aralkyl or aryl, R.sub.2 and R.sub.3 are alkyl, and n is 1 or 2) an esterase encoded by the DNA fragment, a recombinant plasmid containing the DNA fragment, a microorganism transformed with the recombinant plasmid and methods of producing optically active carboxylic acids and their enantiomeric esters.

Abstract: A method for culturing cells by supplying oxygen to a culture medium through a multilayer composite membrane consisting of a porous layer(s) and a nonporous layer(s) having a thickness of less than 10 micrometers laminated one after the other. By using this multilayer composite membrane for supplying oxygen to the culture medium, oxygen can be supplied to the culture medium and/or the culture broth without causing foaming in the culture medium, cell growth inhibition or reduction in productivity of cellular products.

Abstract: Process for racemizing an optically active carboxylic acid ester of the formula (1): ##STR1## wherein R.sub.1 is alkyl, aralkyl or aryl, R.sub.2 and R.sub.3 independently are alkyl, and n is 1 or 2, which comprises contacting the compound of the formula (1) with an amine compound.

Abstract: A process for the preparation of an organic ester of ascorbic acid or erythorbic acid represented by the general formula (II) or (III): ##STR1## wherein R.sub.1 is alkyl, aralkyl, or aryl, by reacting ascorbic acid or erythorbic acid with an organic acid or an ester thereof of the general formula (I) :R.sub.1 COOR.sub.2 (I)wherein R.sub.1 is as defined above and R.sub.2 is hydrogen, methyl, ethyl or propyl, in an organic solvent in the presence of an ester hydrolase.

Abstract: A process for the preparation of an organic ester of ascorbic acid or erythorbic acid represented by the general formula (II) or (III): ##STR1## wherein R.sub.1 is alkyl, aralkyl, or aryl, by reacting ascorbic acid or erythorbic acid with an organic acid or an ester thereof of the general formula (I):wherein R.sub.1 is as defined above and R.sub.2 is hydrogen, methyl, ethyl or propyl, in an organic solvent in the presence of an ester hydrolase.

Abstract: High molecular weight hyaluronic acid can be efficiently produced by incorporating one or more compounds having at least one aromatic ring to which one or more hydroxyl groups are attached into a medium for producing hyaluronic acid by a bacterium capable of producing hyaluronic acid. By using this method, a sufficient amount of hyaluronic acid can be easily obtained without decomposing the high molecular structure of hyaluronic acid so that the process for isolating and purifying hyaluronic acid from the medium can be simplified.

Abstract: Organic carboxylic acid ester represented by the formula (II): ##STR1## wherein R.sub.1 is an alkyl, an aralkyl or an aryl group; R.sub.2 is an alkyl group; R.sub.3 is an alkyl group; n is 1 or 2, are synthesized in racemic form, and then the acid ester (II) is treated with a source containing enzyme capable of rearranging with or without asymmetrically hydrolyzing ester bond until either a d-form or 1-form optically active carboxylic acid ester represented by the formula (II) with or without the antipode acid thereof is produced.

Abstract: Immobilized enzymes or microorganisms are prepared by dispersing lumps of ice containing an enzyme or microorganism in an organic solvent having a water-insoluble high-molecular weight substance dissolved therein, and then removing the organic solvent to entrap the ice lumps in the water-insoluble high-molecular weight substance. Deactivation of the enzyme or microorganism by the organic solvent is prevented by the enzyme or microorganism being entrapped in the lumps of ice.