title: Inactivation and stabilization of IgA protease from the human oral bacterium Streptococcus sanguis.
abstract: The oral bacterium, Streptococcus sanguis, secretes an extracellular protease which specifically cleaves immunoglobulin A (IgA). During in vitro growth of Strep. sanguis at 37 degrees C the IgA protease was completely inactivated within 2 h. Lowering the growth temperature to 31 degrees C reduced the inactivation rate 50 per cent and a doubling of enzyme yield was obtained. The IgA protease could be stabilized by the presence of whole human saliva, by a low concentration of IgA, or by inhibition of non-specific protease activity. Therefore, the inactivation of IgA protease appeared to be the cumulative result of thermal denaturation and inactivation by non-specific proteases.
mesh_terms: D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D009055:Mouth / Q000382:microbiology*; D010447:Peptide Hydrolases / Q000378:metabolism*; D011489:Protein Denaturation; D012463:Saliva / Q000378:metabolism; D012697:Serine Endopeptidases; D013298:Streptococcus sanguis / Q000201:enzymology*; D013696:Temperature
chemical_list: D007070:Immunoglobulin A; D010447:Peptide Hydrolases; D012697:Serine Endopeptidases; C021433:IgA-specific serine endopeptidase