Inactivation of epoxide hydrolase by catalysis-induced formation of isoaspartate

Bert van Loo, Hjalmar P. Permentier, Jaap Kingma, Helen Baldascini, Dick B. Janssen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Epoxide hydrolases catalyze hydrolytic epoxide ring-opening, most often via formation of a covalent hydroxyalkyl-enzyme intermediate. A mutant of Agrobacterium radiobacter epoxide hydrolase, in which the phenylalanine residue that flanks the invariant catalytic aspartate nucleophile is replaced by a threonine, exhibited inactivation during conversion when the (R)-enantiomer of para-nitrostyrene epoxide was used as substrate. HPLC analysis of tryptic fragments of the epoxide hydrolase, followed by MALDI-TOF and TOF/TOF analysis, indicated that inactivation was due to conversion of the nucleophilic aspartate into isoaspartate, which represents a novel mechanism of catalysis-induced autoinactivation. Inactivation occurred at a lower rate with the (S)-enantiomer of para-nitrostyrene epoxide, indicating that it is related to the structure of the covalent hydroxyalkyl-enzyme intermediate.

Original languageEnglish
Pages (from-to)1581-1586
Number of pages6
JournalFEBS Letters
Volume582
Issue number11
Early online date10 Apr 2008
DOIs
Publication statusPublished - 14 May 2008
Externally publishedYes

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