Immunostimulating hexapeptide from human casein: amino acid sequence, synthesis and biological properties

Abstract
A hexapeptide obtained from human casein by enzymatic digestion has been purified, sequenced and synthesized; its structure is: Val‐Glu‐Pro‐Ile‐Pro‐Tyr. In vitro this hexapeptide stimulates the phagocytosis of opsonized sheep red blood cells by murine peritoneal macrophages. Administered intravenously to adult mice, it enhances the resistance to infection with Klebsiella pneumoniae.