Observations on the lipolytic and melanotropic activities of the pineal gland.

An extract of ovine and bovine pineal glands (labeled Precipitate II) has previously been shown to possess lipolytic activity on rabbit adipose tissue. This extract also causes darkening of the frog’s skin in vivo and in vitro. Both lipolytic and melanotropic activities are abolished by trypsin and chymotrypsin. Fractionation of ovine pineal Precipitate II by the sequence, chromatography on diethylaminoethyl cellulose + chromatography on carboxymethyl cellulose + gel filtration (repeated once) on Sephadex G-25, concentrated both activities lOOto lOOO-fold. Only one component was visible in acrylamide gel electrophoretograms of the final concentrate; its volume of elution from Sephadex G-25 indicated a molecular weight of 1000 to 3500; its lipolytic and melantropic potencies were about 10 to 80% those of adrenocorticotropin. The bovine peptide, prepared in a similar way, was closely similar to or identical with the ovine counterpart in electrophoretic mobility, molecular weight, lipolytic and melanotropic potencies, and amino acid composition.