The Action Pattern of Sugarcane-Leaf Amylase

Abstract

The action pattern of sugarcane leaf amylase was investigated by paper chromatographic techniques. The enzyme was extracted with water from lyophilized leaf tissues, and precipitated by ammonium sulfate between 48- and 60-percent saturation. Aliquots were removed from enzyme-starch digests and inactivated in boiling water at intervals ranging from 5 minutes to 72 hours. Samples were spotted on Whatman No. 1 filter paper, irrigated with butanol-pyridine-water (6:4:3, v/v), and products identified by the silver nitrate technique. The initial and only major product was glucose. No maltose was detected, and oligosaccharides appeared only under conditions of excessively high enzyme concentration or prolonged reaction period. Preparations which appeared to contain distinct amylases on the basis of solubility and pH optima produced only glucose. Substrates hydrolyzed included soluble potato starch, cornstarch, amylose, amylopectin, and glycogen. Glucose was the lone product in each instance. Inulin was not attacked. Maltose was not affected by the enzyme preparation. Glucose produced by enzyme action on starch remained stable. A secondary sugar was formed after invertase preparation was introduced into the digest. This possibly represents an epimerase action upon the newly liberated glucose, but evidence also supports maltose and possibly oligosaccharide synthesis from the glucose product. It was concluded that cane amylase is a glucosidase with very general substrate specificity. The action pattern is explained by random encounter of enzyme with substrate, specificity of action at polymer termini, and a nonspecific internal action dependant upon enzyme concentration and time.