Isolation, purification and amino acid sequence of a tripeptide from bovine pineal tissue displaying antigonadotropic properties.

Studies were performed to isolate peptides displaying antigonadotropic properties from bovine pineal tissue. Inhibition of compensatory ovarian hypertrophy in adult mice was used as an index of activity to guide the purification of a bovine pineal extract in order to isolate these antigonadal peptides. Defatted bovine pineal glands were extracted with acetic acid and further purified by cation-exchange chromatography, gel filtration and paper electrophoresis. The electrophoretogram revealed sixteen ninhydrin spots, of which four were antigonadotropic. One of these fractions was subjected to paper chromatography which yielded two antigonadal fractions. Amino acid analysis of each of these fractions indicated that one was in pure form and the sequence was found to be threonylserinyllysine. The other fraction was heterogeneous, but contained no lysine. Analysis of the amino acid content of the other antigonadal fractions obtained after electrophoresis indicated the possibility that other peptides were present, but did not suggest the presence of arginine vasotocin.