A rennin-sensitive bond in αs1Β-casein

Abstract
Rennin acts on a specially sensitive bond in αs1 B-casein to produce a basic peptide containing residues 1–23 of the original protein. At pH 6·4 and 30°C, the action is specific and rapid, the kinetic constants being Km 4·5×10−4M, Kcat 3·8 s−1, and kcat/Km 0·85×104 s−1 M−1. Pepsin, and a protease impurity in the acid phosphatase from wheat germ, have a similar action.