THE INFLUENCE OF SUBSTRATE STRUCTURE ON THE KINETICS OF THE HYDROLYSIS OF STARCH BY GLUCOAMYLASE

In this research the influence of substrate structure on the kinetics of the enzymatic hydrolysis of starch by glucoamylase was evaluated. F or this purpose, two substrates of different form and molecular weight were used. In one case, the kinetics of the hydrolysis corresponds to a typical Michaelis-Menten behavior; in the other, a decrease of the hydrolysis rate occurred once a determined substrate concentration was surpassed. The structural differences between the starches, which cau sed important differences on the rheological properties of their solut ions, justify the observed differences in their behavior. Branching of the substrate exerts two opposite effects on the hydrolysis rate beca use it allows the increase of the number of available points for the e nzymatic attack, although the branching increases the steric hindrance s and, consequently, the mass transfer resistances. The balance betwee n these two effects is dearly dependent on the substrate concentration .