Modification of subsite Lys residue induced a large increase in maltosidase activity of Taka-amylase A.
A cross-linked modification of Taka-amylase A (TAA) by o-phthalaldehyde gave two enzymes, M1- and M2-TAA, which had optimum pH lower than that of native TAA by 0.5 to 1.0 pH units. The modified enzymes showed higher maltosidase activity, and produced glucose even at the initial period of hydrolysis, in contrast to the native TAA. The modification caused more than a 500-fold decrease in the k0 value of native TAA for alpha-amylase activity, but a definite increase in k0 value of 109. 1 min-1 (native TAA) to 460.0 min-1 (M1-TAA) and 147.1 min-1 (M2-TAA) for maltotriose was evidence for improvement of maltosidase activity of modified enzymes.
Kobayashi
M
M
National Food Research Institute, Ibaraki, Japan.
Miura
M
M
Ichishima
E
E
D000596:Amino Acids; D001236:Aspergillus oryzae / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008320:Maltose / Q000031:analogs & derivatives / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000737:chemistry* / Q000187:drug effects; D009764:o-Phthalaldehyde / Q000494:pharmacology
D000596:Amino Acids; D009844:Oligosaccharides; D009764:o-Phthalaldehyde; D008320:Maltose; C009819:maltotetraose; D000516:alpha-Amylases