Substrate-binding recognition and specificity of trehalose phosphorylase from Schizophyllum commune examined in steady-state kinetic studies with deoxy and deoxyfluoro substrate analogues and inhibitors.

Trehalose phosphorylase is a component of the alpha-D-glucopyranosyl alpha-D-glucopyranoside (alpha,alpha-trehalose)-degrading enzyme system in fungi and it catalyses glucosyl transfer from alpha,alpha-trehalose to phosphate with net retention of the anomeric configuration. The enzyme active site has no detectable affinity for alpha,alpha-trehalose in the absence of bound phosphate and catalysis occurs from the ternary complex. To examine the role of non-covalent enzyme-substrate interactions for trehalose phosphorylase recognition, we used the purified enzyme from Schizophyllum commune and tested a series of incompetent structural analogues of the natural substrates and products as inhibitors of the enzyme.