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α‐Galacturonidase(s): A new class of Family 4 glycoside hydrolases with strict specificity and a unique CHEV active site motif
Author(s) -
Thompson John,
Pikis Andreas,
Rich Jamie,
Hall Barry G.,
Withers Stephen G.
Publication year - 2013
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2013.02.004
Subject(s) - glycoside hydrolase , glycosidic bond , active site , enzyme , phylogenetic tree , chemistry , stereochemistry , crystal structure , biochemistry , biology , crystallography , gene
The catalytic activity of the Family 4 glycosidase LplD protein, whose active site motif is CHEV, is unknown despite its crystal structure having been determined in 2008. Here we identify that activity as being an α‐galacturonidase whose natural substrate is probably α‐1,4‐di‐galacturonate (GalUA 2 ). Phylogenetic analysis shows that LplD belongs to a monophyletic clade of CHEV Family 4 enzymes, of which four other members are also shown to be galacturonidases. Family GH 4 enzymes catalyze the cleavage of the glycosidic bond, via a non‐canonical redox‐assisted mechanism that contrasts with Koshland's double‐displacement mechanism.