Sleep-promoting factor S: purification and properties.

Abstract
Sleep-promoting factor was purified from acid/acetone extracts of whole brains of rabbits and from brainstems of slaughterhouse cattle. Intraventricular infusion of extracts purified by means of ion exchange and gel filtration induced excess slow-wave sleep in rabbits for 5-10 h. The procedure is simple and provides material suitable for physiological studies. Further treatment by partition chromatography and electrophoresis yielded an active product that was purified at least 106-fold. This product was inactivated by incubation with mixed carboxypeptidases A and B. Amino acid analysis of acid hydrolysates indicated that the effective dose was less than 150 pmol/rabbit and the original concentration in brain tissue was of the order of 30 pmol/g of brain.