Stereochemistry of the hydrolysis of trehalose by the enzyme trehalase prepared from the flesh fly Sarcophaga barbata.

1. The enzyme trehalase was prepared from whole flesh flies, Sarcophaga barbata. 2. The rate of mutorotation of glucose released by the enzyme was compared with that of alpha-D-glucose, beta-D-glucose and an equimolar mixture of the two. 3. Derivatives of the glucose released by the enzyme were prepared and analysed by gas chromatography for anomeric composition. 4. The enzyme was incubated with trehalose in a medium enriched with H218O and the glucose was analysed by gas chromatography/mass spectrometry. 5. It was found that an equimolar mixture of alpha-D-glucose and beta-D-glucose is formed on hydrolysis of trehalose by trehalase and 18O is incorporated into beta-D-glucose. 6. These results indicate that there is an inversion of configuration at C-1 of trehalose on hydrolysis and that the hydrolysis proceeds by a bimolecular nucleophilic substitution mechanism.