Open AccessStructure of l ‐rhamnose isomerase in complex with l ‐rhamnopyranose demonstrates the sugar‐ring opening mechanism and the role of a substrate sub‐binding site
Author(s) -
Yoshida Hiromi,
Yoshihara Akihide,
Teraoka Misa,
Yamashita Satoshi,
Izumori Ken,
Kamitori Shigehiro
Publication year - 2013
Publication title -
febs open bio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.718
H-Index - 31
ISSN - 2211-5463
DOI - 10.1016/j.fob.2012.11.008
Subject(s) - rhamnose , isomerase , chemistry , isomerization , pyranose , stereochemistry , catalysis , ring (chemistry) , substrate (aquarium) , biochemistry , galactose , enzyme , organic chemistry , biology , ecology
l ‐Rhamnose isomerase ( l ‐RhI) catalyzes the reversible isomerization of l ‐rhamnose to l ‐rhamnulose. Previously determined X‐ray structures of l ‐RhI showed a hydride‐shift mechanism for the isomerization of substrates in a linear form, but the mechanism for opening of the sugar‐ring is still unclear. To elucidate this mechanism, we determined X‐ray structures of a mutant l ‐RhI in complex with l ‐rhamnopyranose and d ‐allopyranose. Results suggest that a catalytic water molecule, which acts as an acid/base catalyst in the isomerization reaction, is likely to be involved in pyranose‐ring opening, and that a newly found substrate sub‐binding site in the vicinity of the catalytic site may recognize different anomers of substrates.