Biopolymeric substrate structural effects of α-amylase-catalysed amylose depolymerization

Amylose depolymerization kinetics, catalysed with α-amylase, have been studied in mixed aqueous-dimethyl sulfoxide (DMSO) solvents and similar aqueous-DMSO solvents containing butanol. It is determined that the observed depolymerization kinetics are affected by biopolymeric substrate conformations. It is found that substrate conformation strongly influences measured enzymatic activity. Soluble substrates exhibit rapid hydrolysis rates compared to insoluble substrates. Moreover, enzymatic activity is also affected by biopolymeric substrate structure (particularly crystalline structure) in precipitated states. Both the crystalline type and the degree of crystallinity are shown to contribute to the observed kinetics. Of these two parameters, crystalline type is shown to be a more dominant effect than degree of crystallinity in reducing reaction rates. Relative rates of depolymerization for various amylose substrate conformations are presented. The results imply an interrelationship between enzyme action and polymeric substrate conformation. These results suggest that enzymes can “recognize” substrate ternary and quaternary structures and that their catalytic activities reflect this recognition.