1FH9

CRYSTAL STRUCTURE OF THE XYLANASE CEX WITH XYLOBIOSE-DERIVED LACTAM OXIME INHIBITOR

1FH9 の概要

• エントリーDOI: 10.2210/pdb1fh9/pdb
• 関連するPDBエントリー: 1FH8 1FHD 1exp 1fh7 1xyl 2exo
• 分子名称: BETA-1,4-XYLANASE, beta-D-xylopyranose-(1-4)-(2Z,3S,4S,5R)-2-hydroxyiminopiperidine-3,4,5-triol (3 entities in total)
• 機能のキーワード: xylanase, glycosyl hydrolase family 10, catalytic mechanism, inhibitor, hydrolase
• 由来する生物種: Cellulomonas fimi
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 34346.20

構造登録者

Notenboom, V.,Williams, S.J.,Hoos, R.,Withers, S.G.,Rose, D.R. (登録日: 2000-07-31, 公開日: 2000-08-23, 最終更新日: 2024-10-30)

主引用文献

Notenboom, V.,Williams, S.J.,Hoos, R.,Withers, S.G.,Rose, D.R.
Detailed structural analysis of glycosidase/inhibitor interactions: complexes of Cex from Cellulomonas fimi with xylobiose-derived aza-sugars.
Biochemistry, 39:11553-11563, 2000

PubMed Abstract: Detailed insights into the mode of binding of a series of tight-binding aza-sugar glycosidase inhibitors of two fundamentally different classes are described through X-ray crystallographic studies of complexes with the retaining family 10 xylanase Cex from Cellulomonas fimi. Complexes with xylobiose-derived aza-sugar inhibitors of the substituted "amidine" class (xylobio-imidazole, K(i) = 150 nM; xylobio-lactam oxime, K(i) = 370 nM) reveal lateral interaction of the "glycosidic" nitrogen with the acid/base catalyst (Glu127) and hydrogen bonding of the sugar 2-hydroxyl with the catalytic nucleophile (Glu233), as expected. Tight binding of xylobio-isofagomine (K(i) = 130 nM) appears to be a consequence of strong interactions of the ring nitrogen with the catalytic nucleophile while, surprisingly, no direct protein contacts are made with the ring nitrogen of the xylobio-deoxynojirimycin analogue (K(i) = 5800 nM). Instead the nitrogen interacts with two ordered water molecules, thereby accounting for its relatively weaker binding, though it still binds some 1200-fold more tightly than does xylobiose, presumably as a consequence of electrostatic interactions at the active site. Dramatically weaker binding of these same inhibitors to the family 11 xylanase Bcx from Bacillus circulans (K(i) from 0.5 to 1.5 mM) is rationalized for the substituted amidines on the basis that this enzyme utilizes a syn protonation trajectory and likely hydrolyzes via a (2,5)B boat transition state. Weaker binding of the deoxynojirimycin and isofagomine analogues likely reflects the energetic penalty for distortion of these analogues to a (2,5)B conformation, possibly coupled with destabilizing interactions with Tyr69, a conserved, catalytically essential active site residue.

PubMed: 10995222
DOI: 10.1021/bi0010625

実験手法

X-RAY DIFFRACTION (1.72 Å)