Effects of Free and Bound Chlorogenic Acid on the In Vitro Digestibility of Ribulose Bisphosphate Carboxylase from Spinach

The effect of free and bound chlorogenic acid on the in vitro digestibility of spinach ribulose bisphosphate carboxylase from spinach or fraction 1 (F‐1) protein was investigated using a pH stat method. The pancreatin digestibility of F‐1 protein was less than that of casein and BSA but greater than 11s soy protein. Noncovalently bound chlorogenic acid increased the initial rate of hydrolysis using both pancreatin and trypsin. Viscosity measurements suggested non‐ covalent binding of chlorogenic acid caused partial unfolding of F‐1 protein making it more susceptible to proteolysis. Covalently bound chlorogenic acid decreased the rates of hydrolysis of F‐1 by both trypsin and pancreatin, and this was correlated with changes in available lysine.