Purification and characterization of the antigonadotropic pineal substance.
Purification by ultrafiltration of the melatonin-free pineal extract proved to have an antigonadotropic activity enabled the authors to obtain two fractions: one with a molecular weight above 10,000 and a second one with a molecular weight under 10,000 daltons. A biologic trial made by applying the mouse uterus weight test showed that both fractions inhibited the stimulating effect of exogenous HCG on the uterus. Ventral prostate weight test applied to rats showed that only the fraction above 10,000 daltons lowered the weight of this organ under basal conditions and that it inhibited the stimulating effect of exogenous testosterone on the prostate. The fraction with a molecular weight above 10,000 daltons contains 76% Lowry proteins from the total pineal extract and 4% aminic nitrogen and in the polyacrylamide gel electrophoresis it appears as two protein bands. The fraction with a molecular weight under 10,000 daltons contains only 20% proteins and 26% aminic nitrogen from the total pineal extract. Paper chromatography of the amino acids has shown that the lower molecular weight fraction does not contain proline, tyrosine, arginine, lysine and histidine and that in both fractions prevail the aspartic and glutamic acids.