tailieunhanh - Báo cáo khoa học: Kinetics of dextran-independent a-(1 fi 3)-glucan synthesis by Streptococcus sobrinus glucosyltransferase I

Glucosyltransferase (GTF)-I from cariogenicStreptococcus sobrinuselon-gates thea-(1fi3)-linked glucose polymer branches on the primer dextran bound to the C-terminal glucan-binding domain. We investigated the GTF-I-catalyzed glucan synthesis reaction in the absence of the primer dextran. The time course of saccharide production during dextran-independent glu-can synthesis from sucrose was analyzed. | IFEBS Journal Kinetics of dextran-independent a- 1 fi 3 -glucan synthesis by Streptococcus sobrinus glucosyltransferase I 11 1 I IZ 1 X z I Al 1 IS I I Ill ll nu. 1 X z nu. I 1 T I I Hideyuki Komatsu Yoshie Abe Kazuyuki Eguchi Hideki Matsuno Yu Matsuoka Takayuki Sadakane1 Tetsuyoshi Inoue2 Kazuhiro Fukui2 and Takao Kodama1 1 Department of Bioscience and Bioinformatics Kyushu Institute of Technology lizuka Japan 2 Department of OralMicrobiology Okayama University Graduate Schoolof Medicine Dentistry and PharmaceuticalScience Japan Keywords enzyme kinetics glucansucrase glucosyltransferase mutans streptococci nigerooligosaccharide Correspondence H. Komatsu Department of Bioscience and Bioinformatics Kyushu Institute of Technology Kawazu 680-4 Iizuka 820-8502 Japan Fax 81 948 29 7801 Tel 81 948 29 7845 E-mail hide@ Received 3 September 2010 revised 18 November 2010 accepted 25 November 2010 doi Glucosyltransferase GTF -I from cariogenic Streptococcus sobrinus elongates the a- 1 fi 3 -linked glucose polymer branches on the primer dextran bound to the C-terminal glucan-binding domain. We investigated the GTF-I-catalyzed glucan synthesis reaction in the absence of the primer dextran. The time course of saccharide production during dextran-independent glucan synthesis from sucrose was analyzed. Fructose and glucose were first produced by the sucrose hydrolysis. Leucrose was subsequently produced followed by insoluble glucan a- 1 fi 3 -linked glucose polymers after a lag phase. High levels of intermediate nigerooligosaccharide series accumulation were characteristically not observed during the lag phase. The results from the enzymatic activity of the acceptor reaction for the nigerooligo-saccharide with a degree of polymerization of 2-6 and methyl a-D-gluco-pyranoside as a glucose analog indicate that the activity increased with an increase in the degree of polymerization. The production of insoluble glucan was numerically