Modulation of substrate preference of thermus maltogenic amylase by mutation of the residues at the interface of a dimer.
To elucidate the relationship between the substrate size and geometric shape of the catalytic site of Thermus maltogenic amylase, Gly50, Asp109, and Val431, located at the interface of the dimer, were replaced with bulky amino acids. The k(cat)/K(m) value of the mutant for amylose increased significantly, whereas that for amylopectin decreased as compared to that of the wild-type enzyme. Thus, the substituted bulky amino acid residues modified the shape of the catalytic site, such that the ability of the enzyme to distinguish between small and large molecules like amylose and amylopectin was enhanced.
Park
Sung-Hoon
SH
Department of Food Science and Agricultural Chemistry, McGill University, Canada.
Kang
Hee-Kwon
HK
Shim
Jae-Hoon
JH
Woo
Eui-Jeon
EJ
Hong
Jung-Sun
JS
Kim
Jung-Wan
JW
Oh
Byung-Ha
BH
Lee
Byong Hoon
BH
Cha
Hyunju
H
Park
Kwan-Hwa
KH
D000596:Amino Acids; D000681:Amylases / Q000235:genetics / Q000378:metabolism*; D000687:Amylopectin / Q000378:metabolism; D000688:Amylose / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D019281:Dimerization; D007700:Kinetics; D009154:Mutation; D013379:Substrate Specificity / Q000235:genetics*; D013824:Thermus / Q000201:enzymology*
D000596:Amino Acids; D000688:Amylose; D000687:Amylopectin; D000681:Amylases