Lack of evidence for sialidase activity in Helicobacter pylori.
The role of sialic acid for the adhesion of Helicobacter pylori to gastric mucosa cells and/or to the mucin layer is still under debate. Several but not all H. pylori strains express a sialic acid-binding adhesin, specific for terminal alpha-2,3-sialic acid residues. Recently, the production of sialidase by H. pylori was reported [Dwarakanath, A.D. et al. (1995) FEMS Immunol. Med. Microbiol. 12,213 216]. We analysed several strains isolated from gastric biopsies cultivated both in liquid media and on agar plates for sialidase. Activity of this enzyme was first assayed using the fluorigenic substrate 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid. Since the fluorimetric assay can give false-positive results caused by non-specific interactions with umbelliferyl-tagged substances, we used also the more sensitive and specific assay with sialyl-[3H]lactitol as a substrate. No evidence for sialidase activity of H. pylori strains, cultivated under both inducible and non-inducible conditions, was obtained.
Hirmo
S
S
Institute of Medical Microbiology, University of Lund, Sweden.
Kelm
S
S
Wadström
T
T
Schauer
R
R
D004415:Dyspepsia / Q000201:enzymology / Q000382:microbiology; D005456:Fluorescent Dyes; D005756:Gastritis / Q000201:enzymology / Q000382:microbiology; D016481:Helicobacter Infections / Q000201:enzymology; D016480:Helicobacter pylori / Q000201:enzymology*; D006801:Humans; D009439:Neuraminidase / Q000378:metabolism*; D010437:Peptic Ulcer / Q000201:enzymology / Q000382:microbiology; D013379:Substrate Specificity
D005456:Fluorescent Dyes; D009439:Neuraminidase