摘要:
Decarbamylases are provided capable of producing D-.alpha.-amino acids by hydrolysis of N-carbamyl-D-.alpha.-amino acids. A source of the decarbamylases is recombinant microorganisms produced by gene manipulation methods. Decarbamylases having improved thermostability can be obtained in which amino acids at a thermostability-related site of a natural decarbamylase have been replaced with other amino acids by mutating a DNA fragment encoding the natural decarbamylase. Recombinant DNA is obtained from a vector DNA and a DNA fragment encoding a natural decarbamylase where the nucleic acid sequence encoding an amino acid at a thermostability-related site is replaced with a nucleic acid sequence encoding another amino acid. The recombinant DNA is used to produce transformants that produce thermostable decarbamylases. The decarbamylases may be immobilized in purified, partially-purified or crude form or in the form of decarbamylase-containing microbial cells on a support such as a polymer having ion exchange groups or covalent bonding groups. The presence of an antioxidant such as dithiothreitol results in an immobilized decarbamylase preparation that can be repeatedly used 30 times or more.
摘要:
The present invention is directed to a gene which is related to a D-N-carbamoyl-.alpha.-amino acid amidohydrolase which is an enzyme capable of converting D-N-carbamoyl-.alpha.-amino acids into D-.alpha.-amino acids; a recombinant plasmid in which a DNA fragment containing the gene is incorporated into a vector; a microorganism belonging to the genus Escherichia, Pseudomonas, Flavobacterium, Bacillus, Serratia, Corynebacterium, or Brevibacterium, which is transformed by incorporating the recombinant plasmid thereinto; a process for the production of D-N-carbamoyl-.alpha.-amino acid amidohydrolases, comprising the steps of cultivating the transformed microorganism and collecting the desired product therefrom; a D-N-carbamoyl-.alpha.-amino acid amidohydrolase obtained by the method; and a process for the production of D-.alpha.-amino acids with the aid of an action of the enzyme. The D-N-carbamoyl-.alpha.-amino acid amidohydrolase can be fixed on a support for immobilization and used as an immobilized enzyme.
摘要:
In a process for the production of a D-.alpha.-amino acid, in which an N-carbamyl-D-.alpha.-amino acid corresponding to the general formula: ##STR1## wherein R represents phenyl, hydroxy-substituted phenyl, substituted or unsubstituted alkyl, or thienyl, is converted by a microbial enzyme in an aqueous medium to a D-.alpha.-amino acid corresponding to the general formula: ##STR2## wherein R is the same as defined above, decarbamylase produced by a microorganism of the genus Comamonas, Blastobacter, Alcaligenes, Sporosarcina, Rhizobium, Bradyrhizobium or Arthrobacter is used as the enzyme converting the N-carbamyl-D-.alpha.-amino acid to the D-.alpha.-amino acid.The conversion of the N-carbamyl-D-.alpha.-amino acids to the D-.alpha.-amino acids is carried out in a neutral to alkaline pH range.
摘要:
A DNA fragment coding for a decarbamylase protein improved in thermostability as the result of replacement of at least one base of a DNA fragment coding for a decarbamylase protein derived from a microorganism with another base and the resultant replacement of at least one of the corresponding amino acids, and its production process; a vector containing the DNA fragment; a transformant obtained by transformation with the vector; as well as a decarbamylase improved in thermostability and its production process. Also disclosed is a process for producing a D-.alpha.-amino acid, which comprises converting an N-carbamoyl-D-.alpha.-amino acid into the corresponding D-.alpha.-amino acid in an aqueous medium by the action of a decarbamylase having a thermostable temperature of 65.degree. C. or higher; and collecting the D-.alpha.-amino acid produced.
摘要:
The present invention is directed to a gene which is related to a D-N-carbamoyl-.alpha.-amino acid amidohydrolase which is an enzyme capable of converting D-N-carbamoyl-.alpha.-amino acids into D-.alpha.-amino acids; a recombinant plasmid in which a DNA fragment containing the gene is incorporated into a vector; a microorganism belonging to the genus Escherichia, Pseudomonas, Flavobacterium, Bacillus, Serratia, Corynebacterium, or Brevibacterium, which is transformed by incorporating the recombinant plasmid thereinto; a process for the production of D-N-carbamoyl-.alpha.-amino acid amidohydrolases, comprising the steps of cultivating the transformed microorganism and collecting the desired product therefrom; a D-N-carbamoyl-.alpha.-amino acid amidohydrolase obtained by the method; and a process for the production of D-.alpha.-amino acids with the aid of an action of the enzyme.The D-N-carbamoyl-.alpha.-amino acid amidohydrolase can be fixed on a support for immobilization and used as an immobilized enzyme.
摘要:
A process for the efficient production of a D-amino acid from the corresponding DL-5-substituted hydantoin by one-step reaction which comprises using a composite immobilized enzyme at a pH about neutrality, said composite immobilized enzyme being obtained by immobilizing a hydantoinase having its optimal pH within an alkaline range and a D-N-carbamyl-.alpha.-amino acid amidohydrolase having its optimal pH about neutrality in a coexisting state on an immobilizing support, simultaneously, is disclosed.
摘要:
In a process for the production of a D-.alpha.-amino acid, in which an N-carbamyl-D-.alpha.-amino acid corresponding to the general formula: ##STR1## wherein R represents phenyl, hydroxy-substituted phenyl, substituted or unsubstituted alkyl, or thienyl, is converted by a microbial enzyme in an aqueous medium to a D-.alpha.-amino acid corresponding to the general formula: ##STR2## wherein R is the same as defined above, decarbamylase produced by a microorganism of the genus Comamonas, Blastobacter, Alcaligenes, Sporosarcina, Rhizobium, Bradyrhizobium or Arthrobacter is used as the enzyme converting the N-carbamyl-D-.alpha.-amino acid to the D-.alpha.-amino acid.The conversion of the N-carbamyl-D-.alpha.-amino acids to the D-.alpha.-amino acids is carried out in a neutral to alkaline pH range.
摘要:
Ethyl-.beta.-benzoyacrylate is reacted with an alkali metal salt of (S)-alanine or an alkali metal salt of N.sup.6 -trifluoroacetyl-L-lysine to form the corresponding Michael addition product, and not less than an equivalent amount of acid is added after completion of the Michael addition to prevent conversion of the (S,S) form of the product to the (R,S) form.
摘要:
Relating to an enzyme capable of efficiently converting a ketone compound to an optically active amino compound by transamination, and a process for preparing an optically active amino compound using the enzyme. An (S)-&agr;-phenethylamine:pyruvate transaminase, which acts on (S)-&agr;-phenethylamine and a ketone compound, thereby catalyzing transamination for forming acetophenone and an amino compound corresponding to the ketone compound; a process for preparing an optically active amino compound using the transaminase; and a method for culturing a microorganism for producing the above transaminase, comprising adding to a medium one or more compounds selected from the group consisting of propylamine, 1-butylamine, 2-butylamine, 2-pentylamine, isopropylamine and isobutylamine as an inducer for the enzyme when a microorganism for producing (S)-&agr;-phenethylamine:pyruvate transaminase is cultured.
摘要:
To provide a method for preparing optically active compounds, which mainly contain (R)-amino compounds, by microbial enzymes efficiently and inexpensively; a polypeptide having stereoselective transaminase activity which can be suitably used for the above preparation method; and a DNA encoding the polypeptide. A method for preparing an optically active amino compound, characterized in stereoselectively transaminating by acting a transaminase on an amino group acceptor, a ketone compound in the presence of an amino group donor, a primary amine; a DNA comprising a nucleotide sequence encoding a polypeptide having stereoselective transaminase activity; and a polypeptide having stereoselective transaminase activity obtainable from a culture of a microorganism belonging to the genus Arthrobacter.