- Preparation of D-amino acids by enzymatic kinetic resolution using a mutant of penicillin-G acylase from E. coli
-
We have demonstrated for the first time that d-glutamine (d-Gln) and d-glutamic acid (d-Glu) can be efficiently obtained in high ee (97% and 90%, respectively) by enzymatic kinetic resolution of d,l-Gln and d,l-Glu. This was achieved by enantioselective conversion of the l-enantiomers to their N-phenylacetyl derivatives in aqueous solution, using a mutant of penicillin-G acylase (PGA) from E. coli and phenylacetic acid methylester as the acyl donor. Kinetic modeling studies suggest that the high ee values obtained are both due to a strong enantiopreference for the l-amino acid in the deacylation step of the covalent enzyme intermediate, as well as to completeness of conversion that is transiently obtained as a result of the distinct preference of the mutant PGA for phenylacetic acid methylester over the N-phenylacetyl-l-amino acid product. For the other amino acids tested (Asn, Asp, and Ser), the highest ee values that were obtained for the remaining d-enantiomer are moderate (50-80%) because of lower enantioselectivity in the enzyme deacylation step and due to less complete conversion of the l-amino acid caused by competition for the active site between the acyl donor and the N-phenylacetyl-l-amino acid that is produced. The results demonstrate that the mutated PGA has great potential for the production of optically active D-amino acids by kinetic resolution.
- Carboni, Chiara,Kierkels, Hans G. T.,Gardossi, Lucia,Tamiola, Kamil,Janssen, Dick B.,Quaedflieg, Peter J. L. M.
-
p. 245 - 251
(2007/10/03)
-
- Enzymic synthesis design and enzymic synthesis of aspartame
-
An enzymic synthesis of aspartame (H-Asp-Phe-OMe) has been designed and realized based on the structure-activity study of thermolysin and penicillin amidase hydrolysis of its p-substituted phenylacetyl derivatives. These compounds meet the structural and energetic requirements of two enzymic binding sites. The peptide sweetener has been prepared by thermolysin - catalyzed condensation of the p-substituted phenylacetyl-Asp-OH and H-Phe-OMe follwed by penicillin amidase - catalyzed deprotection of the resulted aspartame precursors.
- Stoineva,Galunsky,Lozanov,Ivanov,Petkov
-
p. 1115 - 1122
(2007/10/02)
-