Isolation and characterization of a novel D-amidase from Variovorax paradoxus

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

Abstract

Using racemic tert-leucine amide as sole nitrogen source in minimal medium, 162 strains were isolated by enrichment techniques and shown to contain amidase activity. Among these isolates three D-amidase producers were found and identified as Variovorax paradoxus (two strains) and Klebsiella spec. The D-amidase from Variovorax paradoxus was purified to homogeneity by three chromatographic steps. With D,L-Tle-amide as substrate Michaelis-Menten kinetics were observed with a KM of 0.74 mM, a KI of 640 mM and a Vmax of 1.4 U/mg. The amidase has a broad pH-optimum between 7 and 9.5 and a temperature optimum at 47 ± 49 °C. The amidase hydrolyzed amino acid amides as well as carboxamides and 2-hydroxy acid amides. The stereoselectivity of the reaction was variable, however. Hydrolyzing D,L-Tle-amide the enantiomeric ratio E was > 200 resulting in D-Tle with an ee of >99% and up to 47% conversion. Similar results were obtained with D,L-Leu-amide and D,L-Val-amide while D,L-Phe-amide was hydrolyzed with an enantiomeric ratio E of only 5.

Details

Original languageEnglish
Pages (from-to)965-973
JournalAdvanced synthesis & catalysis
Volume2002
Issue number344
Publication statusPublished - 2002
Peer-reviewedYes
Externally publishedYes

External IDs

Scopus 0346007406
ORCID /0000-0002-2912-546X/work/171552003

Keywords

Keywords

  • Biokatalyse, Amidase, Aminosäure, Screening