Porcine-pancreatic alpha amylase hydrolysis of substrates containing 6-deoxy-D-glucose and 6-deoxy-6-fluoro-D-glucose and the specificity of subsite binding

Abstract

Hydrolysis of 6-deoxyamylose and mono-6-deoxy-6-fluorocyclomaltoheptaose by porcine-pancreatic alpha amylase produces low-molecular-weight modified products, which have been analyzed by chemical and chromatographic techniques. Results for both substrates show that modified D-glucose and two isomers of modified maltoses are produced in the enzyme reaction. In addition, the formation of maltoses modified in the nonreducing residue is more favored than the formation of maltoses modified in the reducing residue. These results indicate that productive binding of 6-fluoro- and 6-deoxy-D-glucose residues is permitted at subsites 1 through 4 of the amylase-active site but that binding of these modified residues may be less favorable at subsite 3, the subsite at which catalytic attack occurs.