title: Quantitation of interaction between cytochrome P-450scc and adrenodoxin--analysis in the median UV-region by second derivative spectroscopy.
abstract: Interaction between the essential protein components of the bovine adrenal mitochondrial enzyme system (cytochrome P-450scc, adrenodoxin and adrenodoxin reductase) were studied in the median UV-region utilizing second derivative difference spectroscopy. Complex formation of cytochrome P-450scc with adrenodoxin induces a signal in the second derivative difference spectrum which can be attributed to tyrosine due to its minimum at 283 nm. Based on this signal cytochrome P-450scc was titrated with adrenodoxin in dependence on different effectors (reductase, phospholipid, cholesterol). The dissociation constants (Kd) of the P-450scc/adrenodoxin complexes derived therefrom revealed an increasing affinity between both components starting from titrations in buffer solution without additional components up to the completely reconstituted system. A high affinity between P-450scc and adrenodoxin corresponds to a high turnover rate of cholesterol. Dissociation constants of the P-450scc/adrenodoxin complex were also derived from spectral changes in the Soret region. But these data do not correlate with the substrate turnover.
authors.affiliation: Institute of Bioorganic Chemistry, Academy of Sciences of the BSSR, Minsk, U.S.S.R.
authors.forename: V M
authors.initials: VM
authors.lastname: Shkumatov
authors.forename: G
authors.initials: G
authors.lastname: Smettan
authors.forename: O
authors.initials: O
authors.lastname: Ristau
authors.forename: H
authors.initials: H
authors.lastname: Rein
authors.forename: K
authors.initials: K
authors.lastname: Ruckpaul
authors.forename: V L
authors.initials: VL
authors.lastname: Chaschin
authors.forename: A A
authors.initials: AA
authors.lastname: Akhrem
mesh_terms: D000325:Adrenodoxin; D000818:Animals; D002417:Cattle; D002784:Cholesterol; D002786:Cholesterol Side-Chain Cleavage Enzyme; D004347:Drug Interactions; D005287:Ferredoxin-NADP Reductase; D007700:Kinetics; D010649:Phenylalanine; D013056:Spectrophotometry, Ultraviolet; D014364:Tryptophan; D014443:Tyrosine
chemical_list: D000325:Adrenodoxin; D014443:Tyrosine; D010649:Phenylalanine; D014364:Tryptophan; D002784:Cholesterol; D002786:Cholesterol Side-Chain Cleavage Enzyme; D005287:Ferredoxin-NADP Reductase