title: Characterization by affinity electrophoresis of an alpha-1,6-glucan-binding protein from Streptococcus sobrinus.
abstract: Glucan-binding protein 1 (GBP1), the most abundant glucan-binding protein isolated from culture supernatants of Streptococcus sobrinus 6715-49, has been purified by affinity chromatography on Sephadex G-50 followed by gel permeation chromatography with Bio-Gel P-10. The specificity and affinity of GBP1 for glucans were assessed by affinity electrophoresis. GBP1 did not detectably bind to glucans lacking linear arrays of alpha-1,6 linkages. The association constant for the linear alpha-1,6-glucan Dextran T2000 was 3 x 10(7) M-1. Providing small isomaltosaccharide ligands to compete with this dextran indicated that the binding site maximally accommodated isomaltosaccharides with a degree of polymerization of 8. When glucans produced by purified S. sobrinus glucosyltransferases were tested, GBP1 displayed the highest affinity for the glucan from the soluble-product, primer-independent glucosyltransferase.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D003911:Dextrans / Q000378:metabolism; D004586:Electrophoresis / Q000379:methods; D005936:Glucans / Q000378:metabolism*; D007534:Isomaltose / Q000378:metabolism; D037102:Lectins; D008024:Ligands; D008970:Molecular Weight; D013291:Streptococcus / Q000032:analysis*; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D003911:Dextrans; D005936:Glucans; D037102:Lectins; D008024:Ligands; C037937:glucan-binding proteins; D007534:Isomaltose