Process for producing L-methionine from methional
A method is useful for the biocatalytic synthesis of proteinogenic L-amino acids, such as L-alanine, L-valine, L-methionine, L-leucine, L-isoleucine or L-phenylalanine from a respective aldehyde and carbon dioxide. In particular, the method is useful for the biocatalytic synthesis of L-methionine from 3-methylthio-propanal (“methional”) and carbon dioxide.
1. A method for producing an L-amino acid, comprising:
reacting a mixture comprising an aldehyde, carbon dioxide, a decarboxylase, a corresponding decarboxylase cofactor, and
(a) at least one donor amino acid and an aminotransferase, and/or
(b) NADH, ammonia and/or an ammonium salt and an amino acid dehydrogenase,
thereby producing said L-amino acid or a salt thereof,
wherein the L-amino acid produced is L-methionine and the aldehyde is 3-(methylthio)-propanal (methional),
wherein the decarboxylase is at least one member selected from the group consisting of pyruvate decarboxylase PDC1, which originates from Saccharomyces cerevisiae , phenylpyruvate decarboxylase ARO10, which originates from Saccharomyces cerevisiae , and branched chain decarboxylase KdcA, which originates from Lactococcus lactis,
wherein the aminotransferase, if present, is at least one member selected from the group consisting of methionine aminotransferase YbdL, which originates from E. coli , and aromatic aminotransferase Aro8, which originates from Saccharomyces cerevisiae , and
wherein the amino acid dehydrogenase, if present, is at least one member selected from the group consisting of leucine dehydrogenase (LeuDH), which originates from Bacillus sphaericus , and phenylalanine dehydrogenase (PheDH), which originates from Thermoactinomyces intermedius.
2. The method as claimed in claim 1 , wherein the corresponding decarboxylase cofactor comprises thiamine pyrophosphate.
3. The method as claimed in claim 1 , wherein the donor amino acid is present, is different from the L-amino acid produced, and is at least one L-amino acid selected from the group consisting of L-glutamine, L-glutamate, L-alanine, L-phenylalanine, L-tyrosine, L-leucine, L-isoleucine, L-histidine and L-tryptophan.
4. The method as claimed in claim 1 , wherein the carbon dioxide is applied to the mixture at a pressure from 10 to 7400 kPa.
5. The method as claimed in claim 1 , wherein the mixture further comprises formic acid or a salt thereof and a formate dehydrogenase.
6. The method as claimed in claim 5 , wherein the formate dehydrogenase is at least one member selected from the group consisting of formate dehydrogenase from Pseudomonas sp. and formate dehydrogenase from Candida sp. as well as mutants and variants of these formate dehydrogenases having formate dehydrogenase activity.