Studies on isolation and properties of two isoforms of pituitary gonadotropin from black silver carp, Aristichthys nobilis

1. 1. Two isoforms of gonadotropins (GTHs) were isolated from pituitaries of black silver carp (Aristichthys nobilis Richardson): 37K-bscGTH and 43K-bscGTH. They differed in molecular weight, isoelectric point, and sialic acid content. 2. 2. Amino acid compositions of the respective α and β subunits were similar and the first 10 N-terminal amino acid sequences of the respective α and β subunits of the two GTH isoforms were identical. 3. 3. Both GTHs were similarly potent in stimulating loach ovulation in vivo, and common carp testicular testosterone formation and ovarian follicle estradiol-17β formation in vitro. 4. 4. Preparation of antisera of both GTHs and studies of their crossreactions with various piscine GTHs were reported for the first time.