TYROSINASE ISOFORMS FROM THE FRUITBODIES OF AGARICUS-BISPORUS

Two monomeric tyrosinases were isolated from fruitbodies of Agaricus b isporus strain U1. Both tyrosinases; with pIs ca 5.2 and 5.1, showed a n M(r) of ca 43 kDa under reducing and denaturing conditions and of ca 47 kDa under native conditions, and similar cresolase and catecholase activities of, respectively, 90-120 nkat mg(-1) and 17-18 mu kat mg(- 1). The enzyme preparations were >95% homogeneous. Neither isoform app eared to be glycosylated or phosphorylated. Upon purification the isof orms showed a gradual decrease in pl from ca 5.4-5.6 to ca 5.1-5.2. Co pyright (C) 1996 Elsevier Science Ltd.