Characterization of glucoamylase from Lactobacillus amylovorus ATCC 33621

Abstract

An intracellular glucoamylase, purified from Lactobacillus amylovorus, reacted selectively with polysaccharides. Kinetic studies indicated low affinity for maltose and maltotriose (Km 58 g/ml and 178 g/ml) and higher affinity for starch and dextrin (Km 0.01 g/ml and 0.02 g/ml). Glucoamylase was inhibited almost 50% by 10 mM glucose. Cu2+ and Pb2+ inhibited glucoamylase at 1.0 mM but EDTA and other metal chelators had no effect on the enzyme activity. Acarbose and Tris inhibited the enzyme by 84% and 98%, respectively at 1 mM, while iodoacetate and p-chloromecuribenzoic acid inhibited activity by 98% and 78%, respectively at 10 mM. The purified enzyme was thermolabile at temperatures greater than 55°C and thus has potential for application in the brewing industry.