Structural Studies of the -Glycosidase from Sulfolobus solfataricus in Complex with Covalently and Noncovalent
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- 作者：Tracey M. Gloster ; Shirley Roberts ; Valé ; rie M-A. Ducros ; Giuseppe Perugino ; Mosè ; Rossi ; Roland Hoos ; Marco Moracci ; Andrea Vasella ; and Gideon J. Davies
- 刊名：Biochemistry
- 出版年：2004
- 出版时间：May 25, 2004
- 年：2004
- 卷：43
- 期：20
- 页码：6101 - 6109
- 全文大小：539K
- 年卷期：v.43,no.20(May 25, 2004)
- ISSN：1520-4995
文摘
Transition-state mimicry is increasingly important both to understand enzyme mechanism andto direct the synthesis of putative therapeutic agents. X-ray crystallography is able to provide vitalinformation on the interactions between an enzyme and the potential inhibitor. Here we report the structures,at approximately 2 Å resolution, of a family GH1 
mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-glycosidase from the hyperthermophilic archaeonSulfolobus solfataricus, in complex with both covalently (derived from 2-fluoro-glycosides) andnoncovalently (hydroximolactam) bound inhibitors. The enzyme has broad specificity, accommodatingboth gluco- and galacto-configured substrates, and the crystallographic data demonstrate that the onlydifference in the way these ligands bind lies in the interactions between Gln18, Glu432, and Trp433, andthe hydroxyl group at the O3 and O4 positions. Inhibition by the differently configured ligands was alsoshown to be extremely similar, with Ki values of 1.04 and 1.08 mages/entities/mgr.gif">M for the gluco and galacto epimers,respectively. The noncovalently bound inhibitors have a trigonal anomeric carbon, adopt a 4H3 (half-chair) conformation, and an interaction is formed between O2 and the catalytic nucleophile, all of whichcontribute to (partial) mimicry of the oxocarbenium-ion-like transition state. The inhibition of themages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-glycosidase from S. solfataricus by hydroximolactams is discussed in light of the emerging work onfamily GH1 glycosidase inhibition by a spectrum of putative transition-state mimics.