Role of Dipeptide at Extra Sugar-Binding Space of Thermus Maltogenic Tmylase in Transglycosylation Activity

• Published in: Journal of microbiology and biotechnology Vol. 13; no. 6
• Main Authors: Baek, J.S, Kim, Y.W, Cha, H.J, Kim, Y.R, Moon, T.W, Park, K.H. (Seoul National University, Seoul, Republic of Korea);Kim, T.J. (Chungbuk National University, Cheongju, Republic of Korea);Kim, J.W. (University of Incheon, Republic of Korea);Lee, S.J. (Palo Alto Medical Research Foundation, Palo Alto, Republic of Korea)
• Format: Journal Article
• Language: English
• Published: 01-12-2003
• Subjects: hydrolysis; sugar
• ISSN: 1017-7825

Two conserved amino acid residues in the extra sugar-binding space near the catalytic site of Thermus maltogenic amylase were analyzed for their role in the hydrolysis and transglycosylation activity of the enzyme. Site-directed mutagenesis was carried out by replacing N331 with a lysine , E332 with a histidine , or by replacing both residues at the same time. The measured Km values indicated that affinities toward all substrates tested, including starch, pullulan, beta-cyclomaltodextrin, and acarbose, were lower in all the mutants compared to that of wild-type ThMA, leadin to reduced hydrolysis activity