Fourier transform ion cyclotron resonance MS reveals the presence of a water molecule in an enzyme transition-state analogue complex

Christoph H. Borchers, Victor E. Marquez, Gottfried K. Schroeder, Steven A. Short, Mark J. Snider, J. Paul Speir, Richard Wolfenden

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

The structures of several powerful inhibitors of hydrolytic enzymes resemble that of the altered substrate in the transition state, except that a hydrogen atom replaces one substituent (typically the leaving group). To test the hypothesis that a water molecule might be present in the gap resulting from this replacement, we examined a transition-state analogue complex formed by Escherichia coli cytidine deaminase by Fourier transform ion cyclotron resonance MS in electrospray mode. Upon nebularization from aqueous solution under conditions (pH 5.6) where the enzyme is active, cytidine deaminase remains dimeric in the vapor phase. In the presence of inhibitor, the enzyme's exact mass can be used to infer the presence at each active site of zinc, 5-fluoro-3,4-dihydrouridine, and a single water molecule.

Original languageEnglish
Pages (from-to)15341-15345
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume101
Issue number43
DOIs
Publication statusPublished - 26 Oct 2004
Externally publishedYes

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