1LL4

STRUCTURE OF C. IMMITIS CHITINASE 1 COMPLEXED WITH ALLOSAMIDIN

1LL4 の概要

• エントリーDOI: 10.2210/pdb1ll4/pdb
• 関連するPDBエントリー: 1D2K 1LL6 1LL7
• 分子名称: CHITINASE 1, 2-acetamido-2-deoxy-beta-D-allopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-allopyranose, ALLOSAMIZOLINE, ... (4 entities in total)
• 機能のキーワード: beta-alpha barrel, enzyme-inhibitor complex, hydrolase
• 由来する生物種: Coccidioides immitis
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 177421.79

構造登録者

Bortone, K.,Monzingo, A.F.,Ernst, S.,Robertus, J.D. (登録日: 2002-04-26, 公開日: 2002-09-25, 最終更新日: 2023-08-16)

主引用文献

BORTONE, K.,MONZINGO, A.F.,ERNST, S.,ROBERTUS, J.D.
THE STRUCTURE OF AN ALLOSAMIDIN COMPLEX WITH THE Coccidioides IMMITIS CHITINASE DEFINES A ROLE FOR A SECOND ACID RESIDUE IN SUBSTRATE-ASSISTED MECHANISM
J.Mol.Biol., 320:293-302, 2002

PubMed Abstract: Allosamidin is a known inhibitor of class 18 chitinases. We show that allosamidin is a competitive inhibitor of the fungal chitinase CiX1 from Coccidioides immitis, with a K(i) of 60 nM. We report the X-ray structure of the complex and show that upon inhibitor binding the side-chain of Asp169 rotates to form an ion pair with the oxazolinium cation. The mechanism of action is thought to involve protonation of the leaving group by Glu171 and substrate assistance by the sugar acetamido moiety to form an oxazoline-like intermediate. We converted both amino acid residues to the corresponding amide and found that each mutation effectively abolishes enzyme activity. X-ray structures show the mutant enzymes retain the basic wild-type structure and that the loss of mutant activity is due to their altered chemical properties. The high affinity of allosamidin, and its similarity to the putative reaction intermediate, suggests it is a transition state analog. This helps validate our contention that the role of Asp169 is to electrostatically stabilize the reaction transition state.

PubMed: 12079386
DOI: 10.1016/S0022-2836(02)00444-8

実験手法

X-RAY DIFFRACTION (2.8 Å)