Separation and characterization of four different amylases of Entamoeba histolytica. II. Characterization of amylases

Purified E. histolytica amylases III to VI were characterized by their hydrolytic behaviour towards 4-nitrophenyl alpha-malto-oligosaccharides, malto-oligosaccharides, amylose, amylopectin, glycogen and Y-cyclodextrin. The influence of specific inhibitors on the amylase activity of E. histolytica was examined and compared with typical alpha- and beta-amylases. Amylases III and IV showed alpha-glucosidase and glucosyltransferase activity by cleaving terminal non-reducing glucose from pNPG1 (III, IV) and pNPG2 to pNPG7 (III). Both enzymes were able to cleave malto-oligosaccharides and glucopolysaccharides to a large number of malto-oligosaccharides. Also transglucosidation reactions were observed, but maltose was not hydrolysed. Amylase V showed exoamylase-like properties by preferentially cleaving maltose units from the non-reducing end of synthetic and biogenic malto-oligosaccharides by a multiple-attack mechanism. Amylase VI was characterized as an alpha-amylase, showing great similarities with porcine pancreatic alpha-amylase in the hydrolysis pattern of 4-nitrophenyl alpha-malto-oligosaccharides and glucopolysaccharides. With biogenic malto-oligosaccharides amylase VI showed a transglucosidation reaction.