کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2050121 | 1074155 | 2008 | 6 صفحه PDF | دانلود رایگان |
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.
Journal: FEBS Letters - Volume 582, Issue 11, 14 May 2008, Pages 1581–1586