title: Sterol structural requirements for inhibition of streptolysin O activity.
abstract: Reduced streptolysin O, a toxin produced by certain beta-haemolytic streptococci, lyses human erythrocytes. The reaction is inhibited by cholesterol at concentrations of about 1.0mug/ml. Other sterols inhibit the lysin and there is a specific requirement for a 3beta-hydroxyl group. Inhibition was obtained with 3beta-hydroxychol-5-en-24-oic acid, containing a hydrophilic group at C-24. The mode of inhibition is likely to involve attachment to the fixation site of the lysin which attaches the molecule to cell membranes, probably to membrane cholesterol. A second streptolysin site, concerned in the final haemolytic event, may also be involved. Inhibitors of the latter site have not been characterized, other than antibody with specificity for the site.
mesh_terms: D002776:Cholestanes / Q000494:pharmacology; D002784:Cholesterol / Q000494:pharmacology; D003897:Desmosterol / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects*; D006461:Hemolysis / Q000187:drug effects*; D006801:Humans; D012855:Sitosterols / Q000494:pharmacology; D013261:Sterols / Q000494:pharmacology*; D013301:Streptolysins / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: D002776:Cholestanes; D012855:Sitosterols; D013261:Sterols; D013301:Streptolysins; D003897:Desmosterol; D002784:Cholesterol