HELICOBACTER-PYLORI AND PROTEOLYTIC ACTIVITY

Protease activity of 10 different H. pylori strains, purified marker p roteases and protease-positive reference bacteria (Klebsiella ozaenae, Serratia marcescens) were tested against bovine haemoglobin, porcine mucin, bovine serum albumin, gelatin and casein as substrates. After i ncubation in development buffer and subsequent staining with Coomassie blue, protease activity bands were demonstrated as transparent spots after polyacrylamide gel electrophoresis (PAGE) on gels with incorpora ted substrate. Presence of protease activity was investigated in a wid e pH range (pH 2.0-9.0). Although marker proteases (0.15-0.2 mu g per slot) as well as protease-positive bacteria (2-30 mu g per slot) clear ly showed proteolytic activity in gels containing 0.1-0.2% protein mt no proteolytic activity was demonstrated in any of the H. pylori strai ns tested. This finding indicates that H. pylori does not possess sign ificant protease activity, as this would have been detected by this se nsitive method.