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Catalytic versatility of trehalase: Synthesis of α-d-glucopyranosyl α-d-xylopyranoside from β-d-glucosyl fluoride and α-d-xylose

✍ Scribed by Takafumi Kasumi; Curtis F. Brewer; Elwyn T. Reese; Edward J. Hehre

Publisher
Elsevier Science
Year
1986
Tongue
English
Weight
848 KB
Volume
146
Category
Article
ISSN
0008-6215

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✦ Synopsis

Trehalase was previously shown (see ref. 5) to hydrolyze alpha-D-glucosyl fluoride, forming beta-D-glucose, and to synthesize alpha, alpha-trehalose from beta-D-glucosyl fluoride plus alpha-D-glucose. Present observations further define the enzyme's separate cosubstrate requirements in utilizing these nonglycosidic substrates. alpha-D-Glucopyranose and alpha-D-xylopyranose were found to be uniquely effective in enabling Trichoderma reesei trehalase to catalyze reactions with beta-D-glucosyl fluoride. As little as 0.2mM added alpha-D-glucose (0.4mM alpha-D-xylose) substantially increased the rate of enzymically catalyzed release of fluoride from 25mM beta-D-glucosyl fluoride at 0 degrees. Digests of beta-D-glucosyl fluoride plus alpha-D-xylose yielded the alpha, alpha-trehalose analog, alpha-D-glucopyranosyl alpha-D-xylopyranoside, as a transient (i.e., subsequently hydrolyzed) transfer-product. The need for an aldopyranose acceptor having an axial 1-OH group when beta-D-glucosyl fluoride is the donor, and for water when alpha-D-glucosyl fluoride is the substrate, indicates that the catalytic groups of trehalose have the flexibility to catalyze different stereochemical reactions.

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