ISOLATION OF A SIALIC ACID-SPECIFIC SURFACE HEMAGGLUTININ OF HELICOBACTER-PYLORI STRAIN NCTC-11637

A deionized water extract of Helicobacter pylori NCTC 11637 contained haemagglutinin activity that was (i) soluble (i.e., not associated wit h particulate material sedimented by centrifugation at 100,000 x g for 1 h), (ii) stable to lyophilization, (iii) heat-labile, (iv) chymotry psin-sensitive, (v) inhibited by fetuin, orosomucoid, and NANLac, but not by asialofetuin and (vi) inactive against guinea pig erythrocytes incubated with Clostridium perfringens neuraminidase, but active again st untreated guinea pig erythrocytes. The data support the idea that t he haemagglutinin is a protein which recognizes the alpha-(2-3) struct ure of sialylated glycoconjugates. Fractionation of the extract by iso electric focusing and by gel filtration with Sephacryl S-400 indicated that the haemagglutinin has a pI of 3.7 and consist of high molecular -weight-protein aggregates. SDS-PAGE analysis of the preparation purif ied by gel filtration showed 3 protein bands at ca. 64 kD, 56 kD and 2 0 kD. Electron microscopy of H. pylori incubated with gold-labelled fe tuin indicated that the haemagglutinin was associated with loosely adh erent material on the bacterial surface, and that the purified haemagg lutinin did not reveal a fimbrial structure. The ability to bind to si alogly-coconjugates on the erythrocyte membrane suggests that the haem agglutinin may be an important colonization factor enabling H. pylori to bind to similar saccharide structures on epithelial cells.