• BMB Reports
• /
• v.31 no.4
• /
• pp.307-327
• /
• 1998

Cytochrome c peroxidase (CcP) is a yeast mitochondrial enzyme which catalyzes the reduction of hydrogen peroxide to water using two equivalents of ferrocytochrome c. The CcP/cytochrome c system has many features which make it a very useful model for detailed investigation of heme protein structure/function relationships including activation of hydrogen peroxide, protein-protein interactions, and long-range electron transfer. Both CcP and cytochrome c are single heme, single subunit proteins of modest size. High-resolution crystallographic structures of both proteins, of one-to-one complexes of the two proteins, and a number of active-site mutants are available. Site-directed mutagenesis studies indicate that the distal histidine in CcP is primarily responsible for rapid utilization of hydrogen peroxide implying significantly different properties of the distal histidine in the peroxidases compared to the globins. CcP and cytochrome c bind to form a dynamic one-to-one complex. The binding is largely electrostatic in nature with a small, unfavorable enthalpy of binding and a large positive entropy change upon complex formation. The cytochrome c-binding site on CcP has been mapped in solution by measuring the binding affinities between cytochrome c and a number of CcP surface mutations. The binding site for cytochrome c in solution is consistent with the crystallographic structure of the one-to-one complex. Evidence for the involvement of a second, low-affinity cytochrome c-binding site on CcP in long-range electron transfer between the two proteins is reviewed.

• Molecules and Cells
• /
• v.22 no.2
• /
• pp.220-227
• /
• 2006

Oxidative alteration of mitochondrial cytochrome c has been linked to disease and is one of the causes of proapoptotic events. We have investigated the modification of cytochrome c by $H_2O_2$. When cytochrome c was incubated with $H_2O_2$, oligomerization of the protein increased and the formation of carbonyl derivatives and dityrosine was stimulated. Radical scavengers prevented these effects suggesting that free radicals are implicated in the $H_2O_2$-mediated oligomerization. Oligomerization was significantly inhibited by the iron chelator, deferoxamine. During incubation of deoxyribose with cytochrome c and $H_2O_2$, damage to the deoxyribose occurred in parallel with the release of iron from cytochrome c. When cytochrome c that had been exposed to $H_2O_2$ was analyzed by amino acid analysis, the tyrosine, histidine and methionine residues proved to be particularly sensitive. These results suggest that $H_2O_2$-mediated cytochrome c oligomerization is due to oxidative damage resulting from free radicals generated by a combination of the peroxidase activity of cytochrome c and the Fenton reaction of free iron released from the oxidatively-damaged protein.

• Korean Journal of Microbiology
• /
• v.29 no.2
• /
• pp.92-96
• /
• 1991

The soluble cytochrome c-551 of photosynthetic bacterium, Rhodopseudomonas gelatinosa ATCC 17013 was purified through a sequene of four step chromatography including CM-cellulose ion-exchange chromatography, DEAE-Sephacel chromatography, Sephacryl s-200 gel permeation chromatography, and HPLC (SP-5PW). The molecular weight of the purified cytochrome c-551 was 14, 600 Da, and this protein shows the absorption peak at 551 nm, 522 nm, and 417 nm as the reduced form, and at 412 nm as the oxidized form. The cytochrome c-551 seems to be a substrate for the terminal oxidase in the electron transport chain.

• Korean Journal of Pharmacognosy
• /
• v.21 no.1
• /
• pp.74-82
• /
• 1990

The effects of naturally occurring furanocoumarins on cytochrome P-450 have been investigated in rat liver microsomes. Incubation of microsomes with an NADPH-generating system and four furanocoumarins such as imperatorin, isoimperatorin, phellopterin and byakangelicin at $37^{\circ}$ in vitro resulted in a significant destruction of cytochrome P-450. A single treatment(50 mg/kg, i.p.) of rats with each furanocoumarin caused a rapid loss of cytochrome P-450 accompanied by the loss of heme from the microsomes but not by the loss of cytochrome $b_5$. It is suggested that cytochrome P-450 is specifically destroyed by furanocoumarins in a metabolic process involving destruction of its heme group and as a consequence, hepatic enzyme activities are depressed markedly.

• BMB Reports
• /
• v.46 no.2
• /
• pp.119-123
• /
• 2013

Methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol), an endogenous neurotoxin, is known to perform a role in the pathogenesis of Parkinson's disease (PD). In this study, we evaluated oxidative modification of cytochrome c occurring after incubation with salsolinol. When cytochrome c was incubated with salsolinol, protein aggregation increased in a dose-dependent manner. The formation of carbonyl compounds and the release of iron were obtained in salsolinol-treated cytochrome c. Salsolinol also led to the release of iron from cytochrome c. Reactive oxygen species (ROS) scavengers and iron specific chelator inhibited the salsolinol-mediated cytochrome c modification and carbonyl compound formation. It is suggested that oxidative damage of cytochrome c by salsolinol might induce the increase of iron content in cells, subsequently leading to the deleterious condition which was observed. This mechanism may, in part, provide an explanation for the deterioration of organs under neurodegenerative disorders such as PD.

• Korean Journal of Microbiology
• /
• v.30 no.2
• /
• pp.101-107
• /
• 1992

Cytochrome c oxida5e from chemotrophically grown R p , geliitinosu was purified by cytochrome c affinity chromatography and DEAE-Sephacel ion exchange chromatography. The molecular weight of the cytochrome c oxidase was approximately 110.000 Da by sephacryl s-300 gel chromatography and approximately 52, 000 Da by SDS-gel electrophoresis, respectively. Therefore. cytochrolne c oxidase of Rps. gehtinosu seems to be dimer. The cytochrome c oxidasc was very sensitive to temperature. It's Km and Vmax were 20 pM and 44 unitlmg protein for horsc heart cytochrome c as a substrate. respectively, and its optimum pH and temperature were 6.4 and 25$^{\circ}$C. respectively. The absorption peaks of the reduced cytochrome c oxidase showed at 554 nm, 523 nm. and 422 nm. The activiiy of cytochrome c oxidase was inhibited by KCN, and NaN3, but not by CO, antimycir~ A. and myxothiazol. The cytochrome c-551 was produced either in phototrophically or chemotrophically grown Rps. gelaiinosci. The rcduced cytochrome c-551 was oxidized by b-type cytochrome c oxidase from Rp.v. gc.lrtino.sc~. Km and Vmax of cytochrome c oxidase was 26 pM and 31 unitlnlg protein For cytochrome c-551 as a substrate. respectively. Thercfore. thc electron transfer chain of chemotrophically grown Rps. glatinosa seems lo be ubiquinol cytochrome bc, complex -'cytochrome c-55lMb-type cytochrome c oxidase+02.

• Journal of environmental and Sanitary engineering
• /
• v.10 no.3
• /
• pp.16-28
• /
• 1995

Influences of capsaicin on the activities of cytochrome P45O of liver cell were studied in rats. Rats were provided food and water ad libitum and capsaicin and methylcellulose were gavaged for 6 days. Body weight gain and liver weight/body weight ratio, microsomal protein content and serum HDL- cholesterol content, the activity of cytochrome P450 and erythromycin demethylase, the activities of ethoxyresorufin and pentoxyresorufin O- dealkylase were determined. Capsaicin increased body weight gain but showed no significant changes on liver weight as compared with control group. Capsaicin increased the microsomal protein significantly but decreased the serum HDL- cholesterol. Capsaicin decreased the microsomal cytochrome P4SO significantly and did not show any influences on erythromycin demethylase ( cytochrome P45O III A ). Capsaicin increased the activity of pentoxyresorufin O- dealkylase ( cytochrome P45O II B) and decreased the activity of ethoxyresorufin O-dealkylase ( cytochrome P45O I A). It might be concluded that capsaicin reduced the microsomal cytochrome P45O and induced the CYP III and inhibited the CYP I A. It also might be concluded that capsaicin had no influence on CYP III A and decreased serum HDL- cholesterol. In these results capsaicin can not be used as an anti- atherosclerotic agent by increasing the CYP III A and HDL- cholesterol but it is considered that the more precise study on these theme is necessary.

• YAKHAK HOEJI
• /
• v.25 no.4
• /
• pp.145-151
• /
• 1981

The effect of ginseng methanol extract on hepatic drug metabolizing enzyme in rat was investigated. The ginseng methanol extract (100mg/kg) was administered orally to Sprague Dawley rats for 7days and the contents of cytochrome $P_{450}$ and NADPH cytochrome c reductase in liver were measured by the method of Stanton et al. and Mazel respectively. The content of liver cytochrome $P_{450}$ and NADPH cytochrome c reductase in the rats treated with ginseng methanol extract (100mg/kg) were increased by 21.9% and l6.6% respectively and their increases were statistically significant. Single i.p. injection of phenobarbital (100mg/kg) to the rats produced approximately 25% increase in cytochrome $P_{450}$ content in this investigation and further stimulation was produced in the rats pretreated with ginseng methanol extract (100mg/kg). On the other hand, single i.p. injection of 95% $CCl_{4}$ (0.5ml/kg) showed 29% decrease in cytochrome $P_{450}$ content and 10.5% decrease in NADPH cytochrome c reductase activity. The degree of inhibition of cytochrome $P_{450}$ content in the rats pretreated with ginseng methanol extract (100mg/kg) was similar to that observed in the $CCl_{4}$ alone treated group, but NADPH cytochrome c reductase activity was increased by 65% in the rats pretreated with ginseng methanol extract (100mg/kg). These results suggest that ginseng is the hepatic drug metabolizing enzyme inducing agent in the rat and the effect is similar to phenobarbital.

• Journal of Life Science
• /
• v.11 no.5
• /
• pp.405-414
• /
• 2001

Protaetia brevitarsis has been utilized as an ingredient of the description for the treatment of patients with chronic hepatic diseases in oriental medicine. This study was attempted to investigate whether Protaetia brevitarsis extract(PBE) protects or modulates the liver injuries induced by carbon tetrachloride or ethanol in Sprageue-Dawley rate. The liver injuries of rats induced by the treatment of carbon tetrachloride or ethanol were manifested by the observation of the significant changes in liver weight, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, serum thiobarbituric acid reactive substances (TBARS), and microsomal detocification enzymes(cytochrome P_450), cytochrome b$_{5}$, and cytochrome b$_{5}$ reductase).The effect of PBF on the liver damage induced by the chemicals was evaluated with the extent modulated in change of biochemical parameters above. Exposure to ethanol alone resulted a significant change in the ration of liver per body weight, ALT activity, and microsomal detoxification enzymes (cytochrome P_450, cytochrome b$_{5}$, and cytochrome b$_{5}$ reductase), but did not significantly changes in the levels of serum AST activity and TBARS. Pretreatment coith PBE did not modulate the alteration of the ratio of liver to body weigth, and the activities of serum aminotransferascs (AST. ALT), TBARS, and micro somal detoxification enzyme (cytochrome p_450, cytochrome b$_{5}$,and cytochrome b$_{5}$ reductase. These result suggested that PBE has not appreciable therapeutic effect on carbon tetrachloride or ethanol induced hepatotoxicity.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1993.04a
• /
• pp.100-100
• /
• 1993

Antiestrogen은 에스트로젠 의존성 유방암 치료에 사용되는 약물로써 표적 세포 내에서 에스트로젠 수용체와 작용하여 세포 증식 억제 작용을 나타내고 동시에 에스트로젠 수용체와는 구분되는 소포체 분획의 antiestrogen specific binding site (AEBS) 와도 결합을 하는 것으로 알려져 있다. 그러나, 아직 이 AEBS의 생리적 또는 약리적 기능은 밝혀져 있지 않다. 따라서 본 실험에서는 AEBS의 기능을 조사하기 위하여 cytochrome P45O III 효소군과 AEBS와의 관계를 자옹 백서를 이용하여 면역 화학 반응 실험 및 경쟁적 결합 반응 실험을 하였고, 그 결과는 다음과 같다. 1) AEBS에 대해서 SKF-525A와 metyrapone은 결합 능력을 나타내었다. 2) 자성쥐에서는 주령이 증가함에 따라 cytochrome P450양이 감소하였다. 3) 자옹성쥐 모두에서 phenobarbital 처치에 의해 cytochrome P450 III 효소양이 증가하였고, AEBS도 증가하였다. 4) 웅성쥐에서는 testosterone에 의하여 AEBS가 증가하였다. 5) 자웅성쥐 모두에 tamoxifen 관류시 cytochrome P450 III 효소양이 증가하였고 estradiol과 병용 관류시에는 tamonifen 단독 관류시보다 감소하였다. 이상의 결과에서 tamoxifen이 cytochrome P450 III을 유도할 수 있는 것으로 사료되며 cytochrome P450 III 효소군과 안티에스트로젠 결합부위와 밀접한 관련이 있는 것으로 생각된다.