title: Protoporphyrin-induced photodynamic effects on band 3 protein of human erythrocyte membranes.
abstract: In previous studies it has been shown that protoporphyrin-induced photodynamic effects on red blood cells are caused by photooxidation of amino acid residues in membrane proteins and by the subsequent covalent cross-linking of these proteins. Band 3, the anion transport protein of the red blood cell membrane, has a relatively low sensitivity to photodynamic cross-linking. This cannot be attributed to sterical factors inherent in the specific localization of band 3 in the membrane structure. Solubilized band 3, for instance, showed a similar low sensitivity to cross-linking. By extracellular chymotrypsin cleavage of band 3 into fragments of 60,000 and 35,000 daltons it could be shown that both fragments were about equally sensitive to photodynamic cross-linking. The 17,000 dalton transmembrane segment, on the other hand, was completely insensitive. Inhibition of band 3-mediated sulfate transport proceeded much faster than band 3 interpeptide cross-linking, presumably indicating that the inhibition of transport is caused by photooxidation of essential amino acid residues or intrapeptide cross-linking. A close parallel was observed between photodynamic inhibition of anion transport and decreased binding of 4,4'-diisothiocyanodihydrostilbene-2,2'-disulfonate (H2DIDS), suggesting that a photooxidation in the immediate vicinity of the H2DIDS binding site may be responsible for transport inhibition.
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000031:analogs & derivatives*; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives; D001457:Anion Exchange Protein 1, Erythrocyte; D001798:Blood Proteins / Q000378:metabolism*; D003432:Cross-Linking Reagents; D003905:Deuteroporphyrins / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008027:Light; D008565:Membrane Proteins / Q000097:blood; D010777:Photochemistry; D011166:Porphyrins / Q000494:pharmacology*; D011524:Protoporphyrins / Q000494:pharmacology*; D013431:Sulfates / Q000097:blood
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D001798:Blood Proteins; D003432:Cross-Linking Reagents; D003905:Deuteroporphyrins; D008565:Membrane Proteins; D011166:Porphyrins; D011524:Protoporphyrins; D013431:Sulfates; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C018564:dihydro-DIDS; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid