Cytochrome c
Structural Formula Vector Image
Title: Cytochrome c
CAS Registry Number: 9007-43-6
Additional Names: Myohematin; hematin-protein
Trademarks: Cytorest (Mochida)
Literature References: Electron transport protein found in the mitochondrial intermembrane space of all eukaryotes. Transfers electrons between complex III and complex IV of the respiratory chain. Synthesized in the cytosol as apocytochrome c, then transported across the mitochondrial outer membrane. Heme lyase covalently attaches the heme c prosthetic group, a derivative of iron protoporphyrin IX, q.v. During apoptosis, cytochrome c is released from the mitochondia and acts as a cofactor for caspase, q.v. activation. Human form consists of a single polypeptide chain of 104 amino acid residues with the heme group covalently attached through thioether linkages at cysteine residues 14 and 17. Isoln from muscle tissue: C. A. MacMunn, Proc. R. Soc. London 39, 248 (1886). Identification and absorption spectra of cellular pigments called cytochromes: D. Keilin, Proc. R. Soc. London Ser. B 98, 312 (1925). Redox function and isoln from baker's yeast: idem, ibid. 106, 418 (1930). Absorption spectrum: M. Dixon et al., ibid. 109, 29 (1931). Improved prepn from vertebrate and invertebrate sources: E. Margoliash, O. F. Walasek, Methods Enzymol. 10, 339 (1967). Isoln and purification from plant sources: M. Richardson et al., Phytochemistry 9, 2271 (1970). Oxidation-reduction potentials: F. L. Rodkey, E. G. Ball, J. Biol. Chem. 182, 17 (1950). First crystn from King penguin: G. Bodo, Nature 176, 829 (1955). Electron transport function in respiration: E. C. Slater, Adv. Enzymol. Relat. Subj. Biochem. 20, 147 (1958). First elucidation of amino acid sequence was horse heart: E. Margoliash et al., J. Biol. Chem. 237, 2148, 2151, 2161 (1962); of human heart: H. Matsubara, E. L. Smith, ibid. 238, 2732 (1963). Crystal structure of horse heart and bonito cytochrome c: R. E. Dickerson et al., J. Biol. Chem. 246, 1511 (1971). Structural properties of apo-, iron-free porphyrin, and native cytochrome c: W. R. Fisher et al., J. Biol. Chem. 248, 3188 (1973). Discovery and characterization of apoptotic function: X. Liu et al., Cell 86, 147 (1996); H. Zou et al., J. Biol. Chem. 274, 11549 (1999). Review of role in apoptosis: X. Jiang, X. Wang, Annu. Rev. Biochem. 73, 87-106 (2004). Reviews: R. Lemberg, J. W. Legge, Hematin Compounds and Bile Pigments (Wiley, New York, 1949); E. Margoliash, A. Schejter, Adv. Protein Chem. 21, 113-286 (1966); H. A. Harbury, R. H. L. Marks, in Inorganic Biochemistry vol. 2, G. L. Eichhorn, Ed. (Elsevier, New York, 1973) pp 902-954. Books: Structure and Function of Cytochromes, K. Okunuki et al., Eds. (University Park Press, Baltimore, 1968) 742 pp; G. W. Pettigrew, G. R. Moore, Cytochromes c: Biological Aspects, (Springer-Verlag, Berlin, 1987) 282 pp.; G. R. Moore, G. W. Pettigrew, Cytochromes c: Evolutionary, Structural and Physicochemical Aspects, (Springer-Verlag, Berlin, 1990) 478 pp.; Cytochrome c: A Multidisciplinary Approach, R. A. Scott, A. G. Mauk, Eds. (University Science, Sausalito, 1996) 738 pp.
Properties: Red, basic, water soluble protein. Mol wt about 12500. pI: 10.65 (0°); 10.05 (20°). E0¢ = +0.254 v (pH 1.75-7.8). Extinction ratio for sequences containing 1 tryptophan: E550 red/E280 ox = 1.25; for sequences containing two tryptophans: E550 red/E280 ox = 1.04-1.06. Reduced form, Ferrocytochrome c: absorption max 416, 520, 550 nm (e416 129.1, e550 29.5 mM); oxidized form, Ferricytochrome c: 279, 360, 410, 530 nm (e410 106.1 mM ). Contains one heme per mole weight of 12,500.
Absorption maximum: absorption max 416, 520, 550 nm; 279, 360, 410, 530 nm

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