Thermostable omega-transaminases

1. An isolated thermostable omega transaminase which comprises the amino acid sequence SEQ ID NO:10.

2. An isolated polynucleotide which encodes the amino acid sequence SEQ ID NO:10.

3. The isolated polynucleotide of claim 2 which comprises the nucleotide sequence SEQ ID NO:9.

4. The isolated polynucleotide of claim 2 which is an expression construct.

5. A method for enantiomeric enrichment of a mixture of two enantiomeric chiral amines comprising contacting:

(a) a mixture comprising a first chiral amine and a second chiral amine which is an enantiomer of the first chiral amine, wherein the first chiral amine has the structural formula:

and wherein the second chiral amine has the structural formula:

wherein each of R 1 and R 2 , when taken independently, is alkyl, arylalkyl, or aryl and may be unsubstituted or substituted with one or more enzymatically non-inhibiting groups, and wherein R 1 and R 2 render the molecule chiral;

(b) a thermostable omega transaminase which comprises the amino acid sequence SEQ ID NO:10; and

(c) an amino acceptor

for a time sufficient to convert the first chiral amine to a ketone such that the amount of the second chiral amine in the mixture is at least about 90% relative to the amount of the first chiral amine.

6. The method of claim 5 wherein the contact is maintained at least until the amount of the second chiral amine in the mixture is at least about 99% relative to the amount of the first chiral amine.

7. The method of claim 5 wherein the one or more enzymatically non-inhibiting groups are selected from the group consisting of halogen, hydroxy, lower alkyl, lower alkoxy, lower alkylthio, cycloalkyl, carbamoyl, mono-(lower alkyl)-substituted carbamoyl, di-(lower alkyl)-substituted carbamoyl, trifluoromethyl, phenyl, nitro, amino, mono-(lower alkyl) substituted amino, di-(lower alkyl) substituted amino, alkylsulfonyl, arylsulfonyl, alkylcarboxamido, arylcarboxamido, 2-methylbutane-1,4-diyl, pentane-1,4-diyl, hexane-1,4-diyl, hexane-1,5-diyl, and 2-methylpentane-1,5-diyl.

8. The method of claim 5 wherein the amino acceptor is a ketocarboxylic acid.

9. The method of claim 8 wherein the ketocarboxylic acid is selected from the group consisting of glyoxalic acid, pyruvic acid, oxalacetic acid, and salts thereof.

10. The method of claim 5 wherein the amino acceptor is selected from the group consisting of oxaloacetic acid and pyruvic acid.

11. A method for stereoselective synthesis of one of two chiral forms of an amine comprising contacting:

(a) a ketone having the structural formula:

wherein each of R 1 and R 2 , when taken independently, is alkyl, arylalkyl, or aryl and may be unsubstituted or substituted with one or more enzymatically non-inhibiting groups;

(b) a thermostable omega transaminase which comprises the amino acid sequence SEQ ID NO:10; and

(c) an amino donor

for a time sufficient to form a substantially greater amount of a first chiral form of the amine than the amount of a second chiral form of the amine.

12. The method of claim 11 wherein the one or more enzymatically non-inhibiting groups are selected from the group consisting of halogen, hydroxy, lower alkyl, lower alkoxy, lower alkylthio, cycloalkyl, carbamoyl, mono-(lower alkyl)-substituted carbamoyl, di-(lower alkyl)-substituted carbamoyl, trifluoromethyl, phenyl, nitro, amino, mono-(lower alkyl) substituted amino, di-(lower alkyl) substituted amino, alkylsulfonyl, arylsulfonyl, alkylcarboxamido, arylcarboxamido, 2-methylbutane-1,4-diyl, pentane-1,4-diyl, hexane-1,4-diyl, hexane-1,5-diyl, and 2-methylpentane-1,5-diyl.

13. The method of claim 11 wherein the amino donor is selected from the group consisting of glycine, L-alanine, L-aspartic acid, S-2-aminobutane, propyl amine, and benzyl amine.