[Inhibition of the motility of the gastrointestinal tract by low-molecular peptides from k-casein].

Two low-molecular peptides, peptide III and peptide IV-1, were isolated from peptic digest of k-casein by Sephadex G-50 and BIO-Gel P-2 chromatography. Intravenous administration of these peptides to dogs at a dose of 0.006 mg/kg inhibited food motility of the stomach and duodenum, but did not change or stimulate fasting motility. The duration of the inhibition was decreased with the diminution of the molecular weight of peptide fractions. Peptide III consisted of two inhibitors. Inhibitor I acted immediately after the injection, while inhibitor 2 acted 60-75 minutes later. Being the natural products of food protein proteolysis, these inhibitors may be apparently used in the clinical practice.