Yeast iso-1-cytochrome c. A 2•8 Å resolution three-dimensional structure determination

摘要: Abstract A molecular replacement approach, augmented with the results of predictive modeling procedures, solvent accessibility studies, packing analyses and translational coefficient searches, has been used to elucidate 2·8 (1 = 0·1 nm) resolution structure yeast iso-1-cytochrome c . An examination polypeptide chain folding this protein shows it have unique conformations in three regions, upon comparison structures other eukaryotic cytochromes These include: residues −5 +1 at N-terminal end chain, which are an extended conformation project large part off surface protein; 19 26, form a β-loop on His 18 ligand side central heme group; and, C-terminal helical segment composed 49 56, serves pocket. Structural studies also show that highly reactive sulfhydryl group Cys102 is buried within hydrophobic region monomer Dimerization through disulfide bond formation between two such would require substantial conformational change helix protein. Another structural feature, trimethylated side-chain Lys72, located near solvent-exposed edge bound prosthetic group. On basis these analysis spatial conservation features pocket conducted. It was found involved could be divided into general classes. The current additional explain altered functional properties observed for mutant proteins.