Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Attachment of washed Mycoplasma gallisepticum cells to glass was quantified with organisms in which membrane lipids were labelled with 3H. Siliconization of the test tubes decreased attachment, while centrifugation increased it. Attachment increased with temperature, decreased with increasing pH and ionic strength of the attachment mixture, but was unaffected by Ca2+, Mg2+ and EDTA. This suggests that ionic bonds, but not salt bridges, participate in the attachment process. Glycophorin, the major receptor responsible for M. gallisepticum attachment to erythrocytes, partially inhibited the attachment of the organisms to glass. However, bovine serum albumin also decreased attachment. Extensive pretreatment of the organisms with trypsin decreased their ability to attach to glass by about 35 to 40%. Trypsin and pronase failed to detach the organisms already bound to glass, suggesting that external mycoplasma cell components, other than membrane proteins, also participate in attachment of the organisms to glass.
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PMID:Adherence of Mycoplasma gallisepticum to glass. 3 84

Glycophorin from porcine erythrocyte membranes was digested with trypsin and chymotrypsin. Some of the peptides were isolated by conventional techniques. The amino acid sequence was determined for two isolated peptides: a chymotryptic glycopeptide of 19 residues and a tryptic peptide of 36 residues which represented the carboxy terminal of the glycophorin.
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PMID:Partial amino acid sequence of glycophorin from porcine erythrocyte membranes. 54 38

Human red blood cell membranes were labeled from within the lipid bilayer by the apolar photosensitive reagent, 5-[125I]iodonaphthyl-1-azide. Glycophorin, the major sialoglycoprotein of the red cell membrane, was purified by two different methods; it contained approximately half of the total label incorporated into membrane proteins. The label was confined to the trypsin-insoluble peptide of glycophorin that includes a sequence of 20, mainly apolar, amino acids. These findings provide direct evidence that the labeled segment resides within the membrane in direct contact with the lipid bilayer, and support the suggestion that glycophorin spans the bilayer through its hydrophobic domain.
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PMID:Red cell membrane glycophorin labeling from within the lipid bilayer. 66 61

Glycophorin was purified from human erythrocyte ghosts by the lithium diiodosalicylate -phenol procedure utilizing 125I-labeled lithium diiodosalicylate. The glycophorin preparation was found to contain 8.9 +/- 2.1 mol lithium diiodosalicylate per mol glycophorin. This bound lithium diiodosalicylate cannot be removed by extensive washings with a variety of polar organic solvents nor by treatment with the detergent, sodium deoxycholate. Further, the hydrophobic peptide produced from glycophorin by trypsin digestion contained 3.4 mol lithium diiodosalicylate per mol peptide.
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PMID:Binding of lithium diiodosalicylate to glycophorin. 67 46

Glycophorin A, a major glycoprotein of the red blood cell, is reconstituted in small lipid vesicles (250-300 A in diameter) by using cholate detergent solubilization followed by rapid removal of cholate on a molecular sieve column. The extent of glycophorin incorporation is found to be critically dependent on the amount of cholate used, with higher amounts yielding vesicles with higher percentages of glycophorin. Vesicles with as much as 1 molecule of protein per 20 molecules of lipid can be prepared. Data on the vesicles obtained by using hydrolytic enzymes such as neuraminidase and trypsin, combined with amino acid analysis, suggest that glycophorin is incorporated in a transbilayer fashion with a high fraction of the molecules oriented with the carbohydrate-containing amino terminus to the vesicle exterior. Interaction of the protein with the hydrophobic portion of the bilayer is apparent in proton nuclear magnetic resonance spectra, and lipid line-width increases have been used to characterize the strength and stoichiometry of interaction. Glycophorin is found to affect directly as many as 40 lipid molecules per molecule of protein; however, the magnitude of the effects is not large.
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PMID:Small unilamellar vesicles containing glycophorin A. Chemical characterization and proton nuclear magnetic resonance studies. 626 87

Glycophorin, the major sialoglycoprotein from the human erythrocyte membrane, has been isolated and recombined with phosphatidylcholine and cholesterol. Sucrose density gradient analysis of the recombinants shows that it is possible not only to recombine this protein with phospholipid, but also with phospholipid-cholesterol mixtures. Surprisingly, by the same analysis, it was possible to make a recombinant with cholesterol and glycophorin, only, in the absence of added phospholipid. The accessibility of the protein to trypsin was ested in each of these recombinants. In all the recombinants which contained either phospholipid, or phospholipid and cholesterol, the protein was protected from extensive hydrolysis. This is consistent with closed vesicles and incorporation of the protein into the recombinant membrane. Extensive hydrolysis of the protein occurred in the cholesterol-glycophorin recombinant indicating some differences in structure. Freeze-fracture electron microscopy of the phospholipid and the phospholipid-cholesterol recombinants showed mostly unilamellar vesicles, 1000 to 5000 A in diameter. Intramembranous particles were observed on both fracture faces, and the fracture planes were those expected for phospholipid bilayers. The glycophorin-cholesterol recombinants also showed fracture planes consistent with bilayers, and revealed intramembranous particles. Pieces of membrane-like structures as well as apparent vesicular structures were observed. Finally in the recombinants of glycophorin with phospholipid and cholesterol, cholesterol is shown to reduce the population of the motionally restricted phospholipid headgroup environment, in proportion to the mole percent cholesterol content.
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PMID:Incorporation of the human erythrocyte sialoglycoprotein into recombined membranes containing cholesterol. 672 89