A NONGLYCOSYLATED, 68-KDA ALPHA-L-FUCOSIDASE IS BOUND TO THE MOLLUSK BIVALVE UNIO-ELONGATULUS SPERM PLASMA-MEMBRANE AND DIFFERS FROM A GLYCOSYLATED 56-KDA FORM PRESENT IN THE SEMINAL FLUID

The male reproductive system of the mollusc bivalve Unio elongatulus c ontains two distinct forms of alpha-L-fucosidase, one present in the g onad fluid and a second one associated with the sperm plasma membrane. Both activities were purified to homogeneity. The soluble seminal pla sma enzyme had an oligomeric MW of 56 kDa as determined by MALDI-TOF m ass spectrometry, whereas the enzyme purified from sperm plasma membra nes had an MW of 68 kDa. Analyzed by lectin blotting with ConA and PNA , the 68 kDa enzyme did not bind either lectin, whereas the 56 kDa for m bound ConA only. Both fucosidases followed a Michaelis-Menten kineti cs with the K-m of the sperm-bound enzyme being 7.1 x 10(-4) M and tha t of the seminal enzyme being 9.1 x 10(-4) M. Both had a pH optimum of 5.0. (C) 1997 Academic Press.