Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.64 (proteinase K)
 4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Heparan sulfate binds to proteins present on the surface of Staphylococcus aureus cells. Binding of 125I-heparan sulfate to S. aureus was time dependent, saturable, and influenced by pH and ionic strength, and cell-bound 125I-heparan sulfate was displaced by unlabelled heparan sulfate or heparin. Other glycosaminoglycans of comparable size (chondroitin sulfate and dermatan sulfate), highly glycosylated glycoprotein (hog gastric mucin), and some anionic polysaccharides (dextran sulfate and RNA) inhibited heparan sulfate binding to various extents. Heat treatment (80 degrees C for 10 min) and treatment of the bacteria with pronase E, proteinase K, pepsin, and chymotrypsin considerably reduced their ability to bind 125I-heparan sulfate, but treatment with trypsin and neuraminidase did not affect binding. Scatchard plot analysis indicated the presence of cell surface components with low affinity (Kd = 3 x 10(-5) M) for heparan sulfate. Cell surface components were released by stirring bacteria with 1 M LiCl at 37 degrees C for 2 h. Proteins of this extract that competitively inhibited binding of 125I-heparan sulfate to S. aureus were isolated by affinity chromatography on heparin-Sepharose. Two proteins having molecular masses of approximately 66 and 60 kDa and the ability to bind 125I-heparan sulfate were obtained. The first 9 amino-terminal amino acid residues of the 66-kDa protein are Asp-Trp-Thr-Gly-Trp-Leu-Ala-Ala-Ala, and the first 4 amino-terminal amino acid residues of the 60-kDa protein are Met-Leu-Val-Thr.
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PMID:Binding of heparan sulfate to Staphylococcus aureus. 154 63

Binding of 125I-heparan sulphate was a common property of Helicobacter pylori strains isolated from patients with gastroduodenal ulcer diseases. Binding was (i) saturable; (ii) reversible by the addition of unlabelled heparan sulphate and heparin; (iii) inhibited by unlabelled heparan sulphate, heparin, and heparin oligosaccharides but not by other glycosaminoglycans of comparable size (chondroitin sulphate and dermatan sulphate) or by highly glycosylated glycoproteins (hog gastric mucin and fetuin); (iv) reduced by heat treatment (80 degrees C, 10 min) and exposure of the bacteria to pronase E, proteinase K, trypsin and chymotrypsin, but unaffected by treatment with pepsin and neuraminidase; and (v) time-, pH-, and ionic strength-dependent. Scatchard plot analysis of the binding data indicated the presence of one class of high-affinity receptor (Kd = 9 x 10(-9) M) for heparan sulphate.
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PMID:Affinity of the gastric pathogen Helicobacter pylori for the N-sulphated glycosaminoglycan heparan sulphate. 768 21

Upon oral infection, Trypanosoma cruzi metacyclic trypomastigotes invade and replicate in the gastric mucosal epithelium, being apparently uniquely specialized for adhesion to mucin and mucosal invasion. Here we investigated the involvement of gp82, the metacyclic-stage-specific surface glycoprotein implicated in host cell entry, in both adhesion to gastric mucin and invasion of the mucosal epithelium upon oral challenge. Metacyclic forms, preincubated with a control monoclonal antibody (MAb) or with MAb 3F6 directed to gp82, were administered orally to BALB/c mice, and parasitemia was monitored. Mice that received parasites treated with MAb 3F6 had greatly reduced parasitemia, displaying at the peak a mean number of blood parasites more than 100-fold lower than that of the control group. MAbs directed to other T. cruzi surface glycoproteins had no such effect. gp82, as either a native or a recombinant molecule, but not the metacyclic trypomastigote surface molecule gp90 or gp35/50, bound to gastric mucin in enzyme-linked immunosorbent assays. MAb 3F6 significantly inhibited the penetration of cultured epithelial HeLa cells by metacyclic forms in the absence or in the presence of gastric mucin. Mucin alone did not affect parasite internalization. Parasite infectivity was not altered by treatment of metacyclic forms with pepsin, to which gp82 was resistant, or with proteinase K, which removed the N-terminal portion of gp82 but preserved its host cell binding site. Taken together, these findings suggest that gp82 mediates the interaction of metacyclic trypomastigotes with gastric mucin and the subsequent penetration of underlying epithelial cells.
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PMID:Involvement of Trypanosoma cruzi metacyclic trypomastigote surface molecule gp82 in adhesion to gastric mucin and invasion of epithelial cells. 1249 11