title: 1H NMR studies of the heme iron coordination in cytochrome c-552 from Euglena gracilis.
abstract: The coordination of the heme iron in cytochrome c-552 from Euglena gracilis was investigated by 1H NMR studies at 360 MHz. The data imply that the axial heme ligands are His-14 and Met-56 in both the oxidized and the reduced protein. Studies of mixed solutions of ferro- and ferricytochrome c-552, which provided much of the information on the heme structure, also showed that the intermolecular electron exchange is characterized by a bimolecular rate constant of 5-10(6) mol-1-s-1 at 29 degrees C, which is three orders of magnitude faster than the corresponding reaction in solutions of mammalian cytochromes c.
mesh_terms: D000818:Animals; D001665:Binding Sites; D003574:Cytochrome c Group; D005056:Euglena gracilis / Q000201:enzymology*; D006418:Heme / Q000032:analysis; D007501:Iron / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D003574:Cytochrome c Group; D006418:Heme; D007501:Iron