Inhibition of Streptococcus mutans 6715 glucosyltransferases by sucrose analogs modified at positions 6 and 6'.
Sucrose derivatives modified at position 6 (6-deoxysucrose, 6-thiosucrose, 6,6'-dithiodisucrose, and 6,6'-dideoxy-6,6'-difluorosucrose) were tested as inhibitors of the two Streptococcus mutans 6715 glucosyltransferases. 6-Deoxysucrose was the best inhibitor studied, competitively inhibiting the soluble-D-glucan forming enzyme (GTF-S) and the insoluble-D-glucan forming enzyme (GTF-I) with Ki values one order of magnitude lower than the sucrose Km values. 6-Thiosucrose was also a competitive inhibitor for both enzymes. 6,6'-Dithiodisucrose and 6,6'-dideoxy-6,6'-difluorosucrose only inhibited GTF-I; 6,6'-dithiodisucrose gave mixed inhibition and 6,6'-dideoxy-6,6'-difluorosucrose gave uncompetitive inhibition. 6-Thiosucrose was a substrate for both enzymes to produce acceptor products when acceptors were present. GTF-I synthesized de novo a water-insoluble, (1----3)-6-thio-alpha-D-glucan from 6-thiosucrose.
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D001667:Binding, Competitive; D002250:Carbon Radioisotopes; D005964:Glucosyltransferases / Q000037:antagonists & inhibitors*; D007700:Kinetics; D013295:Streptococcus mutans / Q000201:enzymology*; D013329:Structure-Activity Relationship; D013395:Sucrose / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*
D002250:Carbon Radioisotopes; D013395:Sucrose; D005964:Glucosyltransferases