Comparison of the action pattern of two high maltose-forming alpha-amylases on linear maltooligosaccharides

The high levels of maltose produced by the maltogenic alpha-amylases from P enicillium expansum and Aspergillus oryzae may be explained by the particip ation of multimolecular reactions. Both enzymes catalyze transglycosylation reactions during the concentration-dependent degradation of maltooligosacc harides produced on hydrolysis of starch. The significantly higher yields o f maltose achieved with the P. expansum alpha-amylase, compared to the A. o ryzae enzyme, appear to be due to the mechanism of action of P, expansum on maltotriose. The A. oryzae enzyme only switches from unimolecular to multi molecular events at high concentrations of the trisaccharide. The P. expans um alpha-amylase, however, catalyzes reactions other than simple hydrolysis at all concentrations of maltotriose tested, resulting in the production o f maltose in excess of glucose from this major intermediate of starch hydro lysis. (C) 1999 Elsevier Science Inc. All rights reserved.