title: Inhibition of the interaction of Streptococcus sanguis with hexadecane droplets by 55- and 60-kilodalton hydrophobic proteins of human saliva.
abstract: The effect of salivary secretions on the hydrophobicity of Streptococcus sanguis was investigated. Pretreatment of the bacteria with paraffin-stimulated whole saliva resulted in a 79% inhibition of adhesion to hexadecane droplets. Column chromatography on Sepharose 4B and sodium dodecyl sulfate gel electrophoretic analysis indicated that the inhibitory activity of saliva resided in a fraction containing material of approximately 60,000 molecular weight. The active components, which we have termed the hydrophobic components (HC), bind to octyl-Sepharose beads. Pretreatment of S. sanguis with HC resulted in a dose-dependent inhibition of the streptococcus-hexadecane interaction that reached a maximum of 85%. Furthermore, HC effectively blocked the ability of S. sanguis to adhere to hydroxyapatite beads coated with either whole saliva or HC. Sodium dodecyl sulfate-polyacrylamide gel analysis indicated that HC eluted from octyl-Sepharose consisted primarily of two proteins (60 kDa and 55 kilodaltons) which could be resolved by high-pressure liquid chromatography. Both of these proteins were able to inhibit the binding of S. sanguis to hexadecane in a dose-dependent manner; however, the 60-kilodalton molecule was slightly more effective in this assay. Amino acid analysis of these proteins showed that both proteins contained a high percentage of nonpolar amino acids. These findings suggest that certain components of saliva influence the interaction of S. sanguis with hydrophobic surfaces.
mesh_terms: D000268:Adhesiveness; D000473:Alkanes; D000596:Amino Acids / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008970:Molecular Weight; D010434:Pepsin A / Q000494:pharmacology; D012471:Salivary Proteins and Peptides / Q000032:analysis / Q000302:isolation & purification / Q000502:physiology*; D013298:Streptococcus sanguis / Q000502:physiology*; D014357:Trypsin / Q000494:pharmacology
chemical_list: D000473:Alkanes; D000596:Amino Acids; D012471:Salivary Proteins and Peptides; D014357:Trypsin; D010434:Pepsin A; C007932:n-hexadecane