title: Isolation and characterization of soluble cytochrome c-553 and membrane-bound cytochrome f-553 from thylakoids of the green alga Scenedesmus acutus.
abstract: Soluble cytochrome c-553 and membrane-bound cytochrome f-553 from the alga Scenedesmus acutus were purified to apparent homogeneity. The properties of cytochrome c-553 are comparable to preparations obtained from other eukaryotic algae, whereas the thylakoid-bound species resembles higher plant cytochrome f. Common characteristics are: 1. An asymmetrical alpha-band at 553 nm. 2. A midpoint redox potential of +38 MV (pH 7.0), with a pH dependency above pH 8.0 of -60mV/pH unit. 3. Formation of a pyridine hemochromogen with a maximum at 550 nm; no adducts with CN- or CO are observed. Distinguishing features are: 1. Cytochrome f-553 has a more complicated beta-band, with maxima at 531.5 and 524 nm, and hence a more complex low-temperature spectrum. Also the positions of the gamma- and delta-bank at 421.5 and 331 nm, respectively, distinguish cytochrome f-553 from cytochrome c-553, with gamma- and delta-bands at 416 and 318 nm. 2. The ferricytochrome c-553 spectrum exhibits a weak band at 692 nm, which is not observed with cytochrome f.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000460:Chlorophyta / Q000032:analysis*; D003574:Cytochrome c Group / Q000302:isolation & purification; D003580:Cytochromes / Q000302:isolation & purification; D045348:Cytochromes f; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000032:analysis*; D008970:Molecular Weight; D010084:Oxidation-Reduction; D013053:Spectrophotometry
chemical_list: D000596:Amino Acids; D003574:Cytochrome c Group; D003580:Cytochromes; C083951:cytochrome c553; D045348:Cytochromes f; C022302:cytochrome C-552