PURIFICATION AND PROPERTIES OF EXTRACELLULAR GLUCOSYLTRANSFERASE FROMSTREPTOCOCCUS-BOVIS

Eight Streptococcus bovis strains were classified into 3 types on the basis of isoelectric point (pI) and molecular mass (M(r)) of extracell ular glucosyltransferase. Strains ATCC 9809, 35034 and 43143 produced glucosyltransferase of pI 3.7 and M(r) 165 kDa; strains ATCC 15351, 27 960 and 33317 produced glucosyltransferase of pI 4.1 and M(r) 140 kDa; strains ATCC 43085 and 43144 did not produce any glucosyltransferase. The glucosyltransferase from S. bovis 9809 was purified by Bio-Gel hy droxyapatite chromatography and DEAE-Toyopearl chrornatography. The S. bovis 9809 glucosyltransferase was immunologically identical with the other 5 S. bovis glucosyltransferases and not related to mutans strep tococcal glucosyltransferases. The specific activity, the optimum pH a nd the K-m value for sucrose were 17.9 U/mg protein, 6.0 and 5.0 mM, r espectively. The first 11 N-terminal amino acid residues of the glucos yltransferase were DETSAVTLTRE, and the region was hydrophilic. The gl ucosyltransferases from S. bovis 9809 and 33317 synthesized from sucro se 1,6-alpha-D-glucan with 9 and 2 mol% 1,3,6-alpha-branched glucose, respectively.