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Publication Abstract from PubMed

We have determined the crystal structure of Trichoderma reesei (Hypocrea jecorina) beta-galactosidase (Tr-beta-gal) at a 1.2A resolution and its complex structures with galactose, IPTG and PETG at 1.5, 1.75 and 1.4A resolutions, respectively. Tr-beta-gal is a potential enzyme for lactose hydrolysis in the dairy industry and belongs to family 35 of the glycoside hydrolases (GH-35). The high resolution crystal structures of this six-domain enzyme revealed interesting features about the structure of Tr-beta-gal. We discovered conformational changes in the two loop regions in the active site, implicating a conformational selection-mechanism for the enzyme. In addition, the Glu200, an acid/base catalyst showed two different conformations which undoubtedly affect the pK(a) value of this residue and the catalytic mechanism. The electron density showed extensive glycosylation, suggesting a structure stabilizing role for glycans. The longest glycan showed an electron density that extends to the eighth monosaccharide unit in the extended chain. The Tr-beta-gal structure also showed a well-ordered structure for a unique octaserine motif on the surface loop of the fifth domain.

Crystal structures of Trichoderma reesei beta-galactosidase reveal conformational changes in the active site.,Maksimainen M, Hakulinen N, Kallio JM, Timoharju T, Turunen O, Rouvinen J J Struct Biol. 2011 Apr;174(1):156-63. Epub 2010 Dec 3. PMID:21130883^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.