PURIFICATION AND CHARACTERIZATION OF TREHALOSE PHOSPHORYLASE FROM THECOMMERCIAL MUSHROOM AGARICUS-BISPORUS

Trehalose phosphorylase (EC 2.4.1.64) from Agaricus bisporus was purif ied for the first rime from a fungus. This enzyme appears to play a ke y role in trehalose metabolism in A. bisporus since no trehalase or tr ehalose synthase activities could be detected in this fungus. Trehalos e phosphorylase catalyzes the reversible reaction of degradation (phos phorolysis) and synthesis of trehalose. The native enzyme has a molecu lar weight of 240 kDa and consists of four identical 61-kDa subunits. The isoelectric point of the enzyme was pH 4.8. The optimum temperatur e for both enzyme reactions was 30 degrees C. The optimum pH ranges fo r trehalose degradation and synthesis were 6.0-7.5 and 6.0-7.0, respec tively. Trehalose degradation was inhibited by ATP and trehalose analo gs, whereas the synthetic activity was inhibited by P-i (K-i = 2.0 mM) . The enzyme was highly specific towards trehalose, P-i, glucose and a lpha-glucose-1-phosphate. The stoichiometry of the reaction between tr ehalose, P-i, glucose and alpha-glucose-1-phosphate was 1:1:1:1 (molar ratio). The K-m values were 61, 4.7, 24 and 6.3 mM for trehalose, P-i , glucose and alpha-glucose-1-phosphate, respectively. Under physiolog ical conditions, A. bisporus trehalose phosphorylase probably performs both synthesis and degradation of trehalose. (C) 1998 Elsevier Scienc e B,V. All rights reserved.