Fast photochemical reactions of cytochrome P450 at subzero temperatures. 1979

C Bonfils, and J L Saldana, and P Debey, and P Maurel, and C Balny, and P Douzou

Several reactions of the cytochrome P450 multi-step cycle have been studied by fast light activation combined with subzero temperatures. A flash device was adapted to an Aminco-Chance DW 2 spectrophotometer equipped for subzero temperature thermostatisation. The first electron can be introduced into the cycle by non specific reducing agents such as reduced flavin mononucleotide (FMNH2) or methylviologen radical (MV.). This first reduction remains a fast process even at subzero temperatures. The oxy-compound Fe2+-O2 can thus be formed either directly from Fe2+ or via the photodissociation of the carboxy-ferro adduct. Fe2+-O2 is stable at subzero temperatures towards spontaneous autoxidation as well as further reduction by FMNH2 or MW.. In addition, the recombination of CO after flash photodissociation of Fe2+-CO was used to study in more details the specific behaviors of the purified microsomal cytochrome.

UI MeSH Term Description Entries
D008861 Microsomes Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed) Microsome
D010084 Oxidation-Reduction A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471). Redox,Oxidation Reduction
D010100 Oxygen An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration. Dioxygen,Oxygen-16,Oxygen 16
D010269 Paraquat A poisonous dipyridilium compound used as contact herbicide. Contact with concentrated solutions causes irritation of the skin, cracking and shedding of the nails, and delayed healing of cuts and wounds. Methyl Viologen,Gramoxone,Paragreen A,Viologen, Methyl
D010777 Photochemistry A branch of physical chemistry which studies chemical reactions, isomerization and physical behavior that may occur under the influence of visible and/or ultraviolet light. Photochemistries
D002248 Carbon Monoxide Carbon monoxide (CO). A poisonous colorless, odorless, tasteless gas. It combines with hemoglobin to form carboxyhemoglobin, which has no oxygen carrying capacity. The resultant oxygen deprivation causes headache, dizziness, decreased pulse and respiratory rates, unconsciousness, and death. (From Merck Index, 11th ed) Monoxide, Carbon
D003080 Cold Temperature An absence of warmth or heat or a temperature notably below an accustomed norm. Cold,Cold Temperatures,Temperature, Cold,Temperatures, Cold
D003577 Cytochrome P-450 Enzyme System A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism. Cytochrome P-450,Cytochrome P-450 Enzyme,Cytochrome P-450-Dependent Monooxygenase,P-450 Enzyme,P450 Enzyme,CYP450 Family,CYP450 Superfamily,Cytochrome P-450 Enzymes,Cytochrome P-450 Families,Cytochrome P-450 Monooxygenase,Cytochrome P-450 Oxygenase,Cytochrome P-450 Superfamily,Cytochrome P450,Cytochrome P450 Superfamily,Cytochrome p450 Families,P-450 Enzymes,P450 Enzymes,Cytochrome P 450,Cytochrome P 450 Dependent Monooxygenase,Cytochrome P 450 Enzyme,Cytochrome P 450 Enzyme System,Cytochrome P 450 Enzymes,Cytochrome P 450 Families,Cytochrome P 450 Monooxygenase,Cytochrome P 450 Oxygenase,Cytochrome P 450 Superfamily,Enzyme, Cytochrome P-450,Enzyme, P-450,Enzyme, P450,Enzymes, Cytochrome P-450,Enzymes, P-450,Enzymes, P450,Monooxygenase, Cytochrome P-450,Monooxygenase, Cytochrome P-450-Dependent,P 450 Enzyme,P 450 Enzymes,P-450 Enzyme, Cytochrome,P-450 Enzymes, Cytochrome,Superfamily, CYP450,Superfamily, Cytochrome P-450,Superfamily, Cytochrome P450
D005486 Flavin Mononucleotide A coenzyme for a number of oxidative enzymes including NADH DEHYDROGENASE. It is the principal form in which RIBOFLAVIN is found in cells and tissues. FMN,Flavin Mononucleotide Disodium Salt,Flavin Mononucleotide Monosodium Salt,Flavin Mononucleotide Monosodium Salt, Dihydrate,Flavin Mononucleotide Sodium Salt,Riboflavin 5'-Monophosphate,Riboflavin 5'-Phosphate,Riboflavin Mononucleotide,Sodium Riboflavin Phosphate,5'-Monophosphate, Riboflavin,5'-Phosphate, Riboflavin,Mononucleotide, Flavin,Mononucleotide, Riboflavin,Phosphate, Sodium Riboflavin,Riboflavin 5' Monophosphate,Riboflavin 5' Phosphate,Riboflavin Phosphate, Sodium
D001426 Bacterial Proteins Proteins found in any species of bacterium. Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial

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