Abstract: The invention concerns a process for the enzymatic preparation of protected di- and oligopeptides and the separation of the protective groups used. The process according to the invention enables peptides to be synthesized simply and economically and the protective group to be separated carefully. The process comprises three reaction steps: 1. Preparation of N-carbamoyl amino acid or N-carbamoyl amino acid derivatives; 2. Formation of the peptide bond between the carbamoyl-protected electrophile and nucelophile; and 3. Separation of the carbamoyl-protective group.

Abstract: The invention involves a procedure for the catalytic enantioselective reduction of ketones to chiral alcohols. Heretofore, this reaction was carried out batch-wise. Because, in this procedure, one utilizes a catalyst increased in size with polymer, it is possible to carry out the reaction in a quasi-continuous manner in a membrane reactor. In contrast to the state of the art, one thus dramatically increases the operative life of the catalyst.

Abstract: Process for the formation of MeO-Peg-protected dihydroquinine or dihydro quinindine derivatives, new dihydroquinine-or dihyroquinidine derivatives as well as the use thereof. It is known that dihydroquinine or dihydroquinidine derivatives can be successfully used as ligands in the enantioselective dihydroxylation. The new disclosed ligand systems based on dihydroquinine/quinidine, unlike the prior art ligands, can be recycled after enantioselective dihydroxylation by precipitating and filtering the reaction medium, and be reused in the reaction medium. Also disclosed are the ligand systems (I) and (IV), process for preparing the same and their use in the enantioselective dihydroxiation of double bonds.

Abstract: The disclosure relates to a process for obtaining optically active L-.alpha.-aminocarboxylic acids from the corresponding racemic D,L,.alpha.-aminocarboxylic acids. The following steps are involved: (a) the D,L,.alpha.-aminocarboxylic acids are acetylated; (b) the N-acetyl-L-.alpha.-aminocarboxylic acid present in the mixture of N-acetyl-D,L,.alpha.-aminocarboxylic acids thus obtained is broken down enzymatically into the L-.alpha.-aminocarboxylic acid; (c) the L-.alpha.-aminocarboxylic acid is separated from the mixture, a quantity of a solution of N-acetyl-D(L)-.alpha.-aminocarboxylic acids and a quantity of acetate equivalent to the L-.alpha.-aminocarboxylic acid being retained; and (d) the N-acetyl-D(L)-.alpha.-aminocarboxylic acid is racemized and recycled for enzymatic breakdown. Known extraction processes involving steps (a) to (d) have the disadvantage of producing large quantities of salt.

Abstract: With known methods of racemizing N-acetyl-D(L)-.alpha.-amino carboxylic acids in the non-aqueous state by heating them to temperatures above room temperatures, significant quantities of by-products are formed, especially acetyl dipeptides. By converting at least a proportion of the N-acetyl-D(L)-.alpha.-amino carboxylic acids to corresponding N-acetyl-D(L)-.alpha.-amino carboxylic acid salts before or during the heating, it is possible to increase the sojourn time of the educt which is to be racemized at higher temperatures without any evident increase in the quantity of by-product formed (in particular acetylated dipeptides). Also disclosed is the production of optically active amino acids by enzymatic splitting of racemic compounds.

Abstract: A plant peptide amidase from the flavedo of oranges is known; this can be obtained only in small quantities and is seasonal. The proposed new enzymes are microbial peptide amidases which can be obtained from micro-organisms recovered from soil samples in a "double screening" and grown. These microbial peptide amidases are particularly useful for (a) the production of peptides and N-terminal-protected amino acids, (b) racemate splitting of N-protected amino acid amides, (c) obtaining non-proteinogenous D-amino acids, and (d) obtaining new N.sub..alpha. -protected D-amino acid amides.

Abstract: The invention relates to novel microorganisms, their use and method of producing L-.alpha.-amino acids. In particular, microorganisms DSM 7329 and 7330 are suitable for the production of L-.alpha.-amino acids from corresponding hydantoins or carbamoyl-.alpha.-amino acids. These novel microorganisms are simple to cultivate and make possible high L-.alpha.-amino acid yields from different substrates.

Abstract: DSM 9771 is a mutant of DSM 7330 which was obtained under selective pressure. Its enzymatic activity is higher by a factor of 2.3 than that of its parent organism. In the presence of an inducer, this activity may be farther increased by a factor of 2.7. The reaction catalyzed by this microorganism or enzymes therefrom is the enantioselective conversion of a D-5-monosubstituted hydantoin or an L-5-monosubstituted hydantoin or a D-N-carbamoyl amino acid or an L-N-carbamoyl amino acid to a corresponding L-.alpha.-amino acid.

Abstract: A method is disclosed by which N-carbamoyl-(R)-tert.-leucine is obtained from tert-butyl hydantoin by means of an (R)-specific hydantoinase, in which N-carbamoyl-(R)-tert.-leucine is converted by reaction with nitrite or an (R)-carbamoylase to (R)-tert-leucine.

Abstract: A water-supported enzymatic reaction is carried out with the substrate and the enzyme present in the solid phase. Either the water does not form a liquid continuum around substrate and enzyme, or the water acts at least partially out of the gas phase, or the water required for the reaction is added via a solid, or at least a part of the water required for the reaction is transferred by means of solid body contacts or by a combination of these means. The reaction mixture can be mixed by ultrasound or turbulence, e.g. in a fluidized bed, or both.

Abstract: The invention relates to a method of preparing 5-(aminoalkyl)-hydantoins with basic side chain in which the protection of the amino function in the side chain is necessary during the formation of the hydantoin requires minimal expense.

Abstract: D-arginine and L-ornithine are prepared by means of the enzymatic conversion of DL-arginine in the presence of an L-arginase which selectively converts L-arginase to L-ornithine, permitting recovery of both D-arginine and L-ornithine.

Abstract: An arginase batch capable of producing ornithine with reduced consumption of enzyme. The arginase batch is stabilized by the addition of a reducing agent in at least a 10-fold molar amount relative to the arginase.

Abstract: The invention relates to novel microorganisms, their use and method of producing L-.alpha.-amino acids. In particular, microorganisms DSM 7329 and 7330 are suitable for the production of L-.alpha.-amino acids from corresponding hydantoins or carbamoyl-.alpha.-amino acids. These novel microorganisms are simple to cultivate and make possible high L-.alpha.-amino acid yields from different substrates.

Abstract: The biocatalytic production of a peptide is carried out with a zymogen instead of the customarily used protease. Since zymogens are proteolytically inactive precursors of proteases, proteolytic side reactions are largely suppressed. Preferably, amino acid esters or peptide esters and C-terminally derivatized amino acids or peptide fragments are coupled to each other. The reaction can also take place in a frozen, aqueous medium. In particular, chymotrypsinogen, trypsinogen, pepsinogen, prorennin or procarboxypeptidase are suitable as zymogens.

Abstract: Protected and unprotected di- or oligopeptides are synthesized by reacting an N-terminally protected .alpha.-amino acid alkyl ester or peptide alkyl ester of the formula X--E--R.sup.1 with an amino acid or a di- or oligopeptide or a derivative thereof of the formula H.sub.2 N--Q--R.sup.2 in aqueous solution in the presence of a hydrolase, and, removing protective groups from the reaction product separated from the reaction mixture, where E is the residue of an .alpha.-amino acid or of a di- or oligopeptide, R.sup.1 is lower alkyl and X is a group which carries a charge or is polar at the pH values used for the reaction and which increases the solubility by a factor >5 compared with compounds wherein X=H, Q is the residue of an amino acid or of a di- or oligopeptide, and R.sup.2 is an optionally esterified or amidated acid group. In a preferred embodiment, the peptide or (.alpha.