Removal of the carboxyl-terminal peptide does not affect refolding or function of bacteriorhodopsin as a light-dependent proton pump.

摘要: Treatment of the purple membrane with carboxypeptidase A, Pronase, or papain, results in cleavage amino acids from carboxyl terminus bacteriorhodopsin, a maximum about 17 being released papain. Protease-treated after denaturation, refolds to native structure, binds retinal as tightly intact protein and, on reconstitution into vesicles, gives full proton translocating activity. The CD spectrum papain-treated shows exciton coupling characteristic membrane. trimeric bacteriorhodopsin dissociates monomers Triton X-100 which, removal detergent, reassociate form oligomeric structures. Chymotrypsin cleaves between 71 and 72 has been previously found for bacteriorhodopsin. resulting fragments C-1 (amino 72-231) C-2 1-71) reassociate, bind retinal, regenerate chromophore, demonstrated corresponding protein. We conclude that COOH-terminal peptide is not required correct refolding denatured tertiary quarternary chromophore regeneration light-driven translocation.