title: Cross-linking of bacteriorhodopsin using specific carboxyl modifications and proteolytic cleavage.
abstract: Specific carboxyl modification of purple membrane using a water-soluble carbodiimide yielded a mixture of oligomers, revealed by gel electrophoresis. Purple membrane pre-treated with papain or trypsin, cleaving the C-terminal tail, showed the same pattern of cross-linked products. Chymotryptic cleavage released amino acids 1-72 (7kD fragment) from the cross-linked products, as it did with native membrane. The tail and helices A and B are not, therefore, involved in carbodiimide-promoted cross-linking. Similar cleavage of a hydrophobic dihydroquinoline-modified sample showed that mainly intra-molecular cross-linking occurs, with little cross-linking between the large and small chymotryptic fragments.
mesh_terms: D001436:Bacteriorhodopsins; D002234:Carbodiimides; D002338:Carotenoids; D002918:Chymotrypsin; D003432:Cross-Linking Reagents; D005022:Ethyldimethylaminopropyl Carbodiimide; D006217:Halobacterium; D010206:Papain; D010446:Peptide Fragments / Q000032:analysis; D011487:Protein Conformation; D011804:Quinolines; D014357:Trypsin
chemical_list: D002234:Carbodiimides; D003432:Cross-Linking Reagents; D010446:Peptide Fragments; D011804:Quinolines; D002338:Carotenoids; D001436:Bacteriorhodopsins; C000470:EEDQ; D002918:Chymotrypsin; D014357:Trypsin; D010206:Papain; D005022:Ethyldimethylaminopropyl Carbodiimide