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Observation of the controlled assembly of preclick components in the in situ click chemistry generation of a chitinase inhibitor.

Proceedings of the National Academy of Sciences of the United States of America (2013-09-18)
Tomoyasu Hirose, Nobuo Maita, Hiroaki Gouda, Jun Koseki, Tsuyoshi Yamamoto, Akihiro Sugawara, Hirofumi Nakano, Shuichi Hirono, Kazuro Shiomi, Takeshi Watanabe, Hisaaki Taniguchi, K Barry Sharpless, Satoshi Omura, Toshiaki Sunazuka
ABSTRACT

The Huisgen cycloaddition of azides and alkynes, accelerated by target biomolecules, termed "in situ click chemistry," has been successfully exploited to discover highly potent enzyme inhibitors. We have previously reported a specific Serratia marcescens chitinase B (SmChiB)-templated syn-triazole inhibitor generated in situ from an azide-bearing inhibitor and an alkyne fragment. Several in situ click chemistry studies have been reported. Although some mechanistic evidence has been obtained, such as X-ray analysis of [protein]-["click ligand"] complexes, indicating that proteins act as both mold and template between unique pairs of azide and alkyne fragments, to date, observations have been based solely on "postclick" structural information. Here, we describe crystal structures of SmChiB complexed with an azide ligand and an O-allyl oxime fragment as a mimic of a click partner, revealing a mechanism for accelerating syn-triazole formation, which allows generation of its own distinct inhibitor. We have also performed density functional theory calculations based on the X-ray structure to explore the acceleration of the Huisgen cycloaddition by SmChiB. The density functional theory calculations reasonably support that SmChiB plays a role by the cage effect during the pretranslation and posttranslation states of selective syn-triazole click formation.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
灰链霉菌来源几丁质酶, lyophilized powder (essentially salt free), ≥200 units/g solid
Sigma-Aldrich
壳质酶 来源于绿色木霉, lyophilized powder, ≥600 units/g solid