Cell-bound cholinesterase inTrichoderma harzianum

Cell-bound cholinesterase enzyme activity is reported for the first time in the mycelium ofTrichoderma harzianum. This enzyme hydrolyzes both the acetylcholine and the butyryl thiocholine esters. TheK_m andV_max for choline ester are 0.69 mM and 1.0 nmol acid released min^–1 g^–1 protein. However, the thiocholine ester has aK_m value of 2.2 mM andV_max value of 3.33 nmol product formed min.^–1 g^–1 protein. The enzyme is inhibited by eserine, a true classical cholinesterase inhibitor.