Interaction of the components of the lactose synthetase system

The modifier action of α-lactalbumin upon galactosyl transferase is pH-dependent. When either N-acetyl glucosamine or glucose is the acceptor, the pH profile of activity is altered in the presence of α-lactalbumin. The effect of α-lactalbumin upon the kinetic constants at a series of pH's has been interpreted in terms of a molecular mechanism of modifier activity.Fluorescence polarization studies indicated that a definite molecular complex between α-lactalbumin and galactosyl transferase is formed in the presence of substrate. Estimates of the equilibrium constants have been made.