CATALYTIC VERSATILITY OF TREHALASE: SYNTHESIS OF α-D-GLUCOPYRANOSYL α-D-XYLOPYRANOSIDE FROM β-D-GLUCOSYL FLUORIDE AND α-d-XYLOSE

Article abstract of DOI:10.1016/0008-6215(86)85022-4

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