Cytochrome c peroxidase

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Cytochrome c peroxidase
Ferrous cytochrome c peroxidase.png
Identifiers
EC no. 1.11.1.5
CAS no. 9029-53-2
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Cytochrome c peroxidase
Identifiers
Organism Saccharomyces cerevisiae
SymbolCCP
UniProt P00431
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Structures Swiss-model
Domains InterPro

Cytochrome c peroxidase, or CCP, is a water-soluble heme-containing enzyme of the peroxidase family that takes reducing equivalents from cytochrome c and reduces hydrogen peroxide to water:

Contents

CCP + H2O2 + 2 ferrocytochrome c + 2H+ → CCP + 2H2O + 2 ferricytochrome c

CCP can be derived from aerobically grown yeast strains and can be isolated in both native and recombinant forms with high yield from Saccharomyces cerevisiae. The enzyme’s primary function is to eliminate toxic radical molecules produced by the cell which are harmful to biological systems. It works to maintain low concentration levels of hydrogen peroxide, which is generated by the organism naturally through incomplete oxygen reduction. When glucose levels in fast growing yeast strains are exhausted, the cells turn to respiration which raises the concentration of mitochondrial H2O2. [1] In addition to its peroxidase activity, it acts as a sensor and a signaling molecule to exogenous H2O2, which activates mitochondrial catalase activity. [2] In eukaryotes, CCP contain a mono-b-type haem cofactor and is targeted to the intermembrane space of the mitochondria. In prokaryotes, CCP contains a c-type diheme cofactor and is localized to the periplasm of the cell. Both enzymes work to resist peroxide-induced cellular stress. [3]

CCP plays an integral role in enabling inter-protein biological electron transfer. The negative charge transfer process is carried out by a complex formed between cytochrome c and cytochrome c peroxidase which occurs in the inter-membrane space of mitochondria. The mechanism involves ferrous cytochrome c (Cc) providing electrons for the Cc-CcP system to reduce hydrogen peroxide to water. [4] The complex is formed by non-covalent interactions. [5]

Cytochrome c peroxidase can react with hydroperoxides other than hydrogen peroxide, but the reaction rate is much slower than with hydrogen peroxide.

It was first isolated from baker's yeast by R. A. Altschul, Abrams, and Hogness in 1940, [6] though not to purity. The first purified preparation of yeast CCP dates to Takashi Yonetani and his preparation by ion exchange chromatography in the early 1960s. The X-ray structure was the work of Thomas Poulos and coworkers in the late 1970s. [7] CCP is the first heme enzyme to have its structure successfully solved through X-ray crystallography.

The yeast enzyme is a monomer of molecular weight 34,000, containing 293 amino acids, and contains as well a single non-covalently bound heme b. It is negatively charged and is a moderately-sized enzyme (34.2 kDa). The apoenzyme, not active and bound to substrates, has an acidic isoelectric point of pH 5.0-5.2. [8] Unusual for proteins, this enzyme crystallizes when dialysed against distilled water. More so, the enzyme purifies as a consequence of crystallization, making cycles of crystallization an effective final purification step.

Much like catalase, the reaction of cytochrome c peroxidase proceeds through a three-step process, forming first a Compound I and then a Compound II intermediate:

CCP + ROOH → Compound I + ROH + H2O
CCP-compound I + e− + H+ → Compound II
Compound II + e− + H+ → CCP
CCP-catalyzed redox cycle CCP-catalyzed redox cycle.png
CCP-catalyzed redox cycle

CCP in the resting state has a ferric heme, and, after the addition of two oxidizing equivalents from a hydroperoxide (usually hydrogen peroxide), it becomes oxidised to a formal oxidation state of +5 (FeV, commonly referred to as ferryl heme. However, both low-temperature magnetic susceptibility measurements and Mössbauer spectroscopy show that the iron in Compound I of CCP is a +4 ferryl iron, with the second oxidising equivalent existing as a long-lived free-radical on the side-chain of the tryptophan residue (Trp-191). [9] In its resting state, the Fe atom (Fe (III)) in the CCP heme is paramagnetic with high spin (S= 5/2). Once the catalytic cycle is initiated, the iron atom is oxidized to form an oxyferryl intermediate (Fe(IV)=O) has low spin (S= 1/2). [4] This is different from most peroxidases, which have the second oxidising equivalent on the porphyrin instead. Compound I of CCP is fairly long-lived, decaying to CCP-compound II with a half-life at room temperature of 40 minutes to a couple hours.

CCP has high sequence identity to the closely related ascorbate peroxidase enzyme.

Amino acid composition

Amino acid analyzer studies reveal presence of residues of Asp, Thr, Ser, Glu, Pro, Gly, Ala, Val, Met, Ile, Leu, Tyr, Phe, Lys, His, Arg, Cys, and Trp in crystalline CCP. The enzyme shows an unusual amino acid pattern compared to other peroxidase. Plant peroxidase such as horseradish peroxidase and pineapple peroxidase B have low lysine, tryptophan, and tyrosine contents and high cysteine content. In contrast, CCP has high lysine, tryptophan, and tyrosine content and low cysteine content. [10] The enzyme contains a 68-residue sequence at the N-terminus of its monomeric protein, which targets it to the inter-membrane space of the mitochondria where it can the complex with cytochrome c and where it carries out its sensor, signaling and catalytic roles. [1] Studies indicate the distal arginine (Arg48), a highly conserved amino acid among peroxidase, plays an important role in the catalytic activity of CCP by controlling its active site through stabilization of the reactive oxyferryl intermediate from control of its access. [11]

Related Research Articles

Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. Autoxidation leads to degradation of organic compounds, including living matter. Antioxidants are frequently added to industrial products, such as polymers, fuels, and lubricants, to extend their usable lifetimes. Food are also treated with antioxidants to forestall spoilage, in particular the rancidification of oils and fats. In cells, antioxidants such as glutathione, mycothiol or bacillithiol, and enzyme systems like superoxide dismutase, can prevent damage from oxidative stress.

<span class="mw-page-title-main">Hydrogen peroxide</span> Chemical compound (H₂O₂); simplest peroxide

Hydrogen peroxide is a chemical compound with the formula H2O2. In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution in water for consumer use, and in higher concentrations for industrial use. Concentrated hydrogen peroxide, or "high-test peroxide", decomposes explosively when heated and has been used both as a monopropellant and an oxidizer in rocketry.

<span class="mw-page-title-main">Peroxisome</span> Type of organelle

A peroxisome (IPA: [pɛɜˈɹɒksɪˌsoʊm]) is a membrane-bound organelle, a type of microbody, found in the cytoplasm of virtually all eukaryotic cells. Peroxisomes are oxidative organelles. Frequently, molecular oxygen serves as a co-substrate, from which hydrogen peroxide (H2O2) is then formed. Peroxisomes owe their name to hydrogen peroxide generating and scavenging activities. They perform key roles in lipid metabolism and the conversion of reactive oxygen species. Peroxisomes are involved in the catabolism of very long chain fatty acids, branched chain fatty acids, bile acid intermediates (in the liver), D-amino acids, and polyamines, the reduction of reactive oxygen species – specifically hydrogen peroxide – and the biosynthesis of plasmalogens, i.e., ether phospholipids critical for the normal function of mammalian brains and lungs. They also contain approximately 10% of the total activity of two enzymes (Glucose-6-phosphate dehydrogenase and 6-Phosphogluconate dehydrogenase) in the pentose phosphate pathway, which is important for energy metabolism. It is vigorously debated whether peroxisomes are involved in isoprenoid and cholesterol synthesis in animals. Other known peroxisomal functions include the glyoxylate cycle in germinating seeds ("glyoxysomes"), photorespiration in leaves, glycolysis in trypanosomes ("glycosomes"), and methanol and/or amine oxidation and assimilation in some yeasts.

<span class="mw-page-title-main">Catalase</span> Biocatalyst decomposing hydrogen peroxide

Catalase is a common enzyme found in nearly all living organisms exposed to oxygen which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting the cell from oxidative damage by reactive oxygen species (ROS). Catalase has one of the highest turnover numbers of all enzymes; one catalase molecule can convert millions of hydrogen peroxide molecules to water and oxygen each second.

<span class="mw-page-title-main">Cytochrome c</span> Protein-coding gene in the species Homo sapiens

The cytochrome complex, or cyt c, is a small hemeprotein found loosely associated with the inner membrane of the mitochondrion where it plays a critical role in cellular respiration. It transfers electrons between Complexes III and IV. Cytochrome c is highly water-soluble, unlike other cytochromes. It is capable of undergoing oxidation and reduction as its iron atom converts between the ferrous and ferric forms, but does not bind oxygen. It also plays a major role in cell apoptosis. In humans, cytochrome c is encoded by the CYCS gene.

<span class="mw-page-title-main">Hemoprotein</span> Protein containing a heme prosthetic group

A hemeprotein, or heme protein, is a protein that contains a heme prosthetic group. They are a very large class of metalloproteins. The heme group confers functionality, which can include oxygen carrying, oxygen reduction, electron transfer, and other processes. Heme is bound to the protein either covalently or noncovalently or both.

<span class="mw-page-title-main">Peroxidase</span> Peroxide-decomposing enzyme

Peroxidases or peroxide reductases are a large group of enzymes which play a role in various biological processes. They are named after the fact that they commonly break up peroxides.

<span class="mw-page-title-main">Heme</span> Chemical coordination complex of an iron ion chelated to a porphyrin

Heme, or haem, is a precursor to hemoglobin, which is necessary to bind oxygen in the bloodstream. Heme is biosynthesized in both the bone marrow and the liver.

<span class="mw-page-title-main">Cytochrome P450</span> Class of enzymes

Cytochromes P450 are a superfamily of enzymes containing heme as a cofactor that mostly, but not exclusively, function as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compounds, as well as for hormone synthesis and breakdown. In 1963, Estabrook, Cooper, and Rosenthal described the role of CYP as a catalyst in steroid hormone synthesis and drug metabolism. In plants, these proteins are important for the biosynthesis of defensive compounds, fatty acids, and hormones.

Respiratory burst is the rapid release of the reactive oxygen species (ROS), superoxide anion and hydrogen peroxide, from different cell types.

<span class="mw-page-title-main">Ascorbate peroxidase</span> Enzyme

Ascorbate peroxidase (or L-ascorbate peroxidase, APX) (EC 1.11.1.11) is an enzyme that catalyzes the chemical reaction

Chloride peroxidase (EC 1.11.1.10) is a family of enzymes that catalyzes the chlorination of organic compounds. This enzyme combines the inorganic substrates chloride and hydrogen peroxide to produce the equivalent of Cl+, which replaces a proton in hydrocarbon substrate:

In enzymology, a lignin peroxidase (EC 1.11.1.14) is an enzyme that catalyzes the chemical reaction

In enzymology, a manganese peroxidase (EC 1.11.1.13) is an enzyme that catalyzes the chemical reaction

<span class="mw-page-title-main">Animal heme-dependent peroxidases</span>

Animal heme-dependent peroxidases is a family of peroxidases. Peroxidases are found in bacteria, fungi, plants and animals. On the basis of sequence similarity, a number of animal heme peroxidases can be categorized as members of a superfamily: myeloperoxidase (MPO); eosinophil peroxidase (EPO); lactoperoxidase (LPO); thyroid peroxidase (TPO); prostaglandin H synthase (PGHS); and peroxidasin.

Haem peroxidases (or heme peroxidases) are haem-containing enzymes that use hydrogen peroxide as the electron acceptor to catalyse a number of oxidative reactions. Most haem peroxidases follow the reaction scheme:

Catalase-peroxidase (EC 1.11.1.21, katG (gene)) is an enzyme with systematic name donor:hydrogen-peroxide oxidoreductase. This enzyme catalyses the following chemical reaction

  1. donor + H2O2 ⇌ oxidized donor + 2 H2O
  2. 2 H2O2 ⇌ O2 + 2 H2O

Fatty-acid peroxygenase is an enzyme with systematic name fatty acid:hydroperoxide oxidoreductase (RH-hydroxylating). This enzyme catalyses the following chemical reaction

<span class="mw-page-title-main">Galactose oxidase</span>

Galactose oxidase is an enzyme that catalyzes the oxidation of D-galactose in some species of fungi.

<span class="mw-page-title-main">Eosinophil peroxidase</span> Protein-coding gene in the species Homo sapiens

Eosinophil peroxidase is an enzyme found within the eosinophil granulocytes, innate immune cells of humans and mammals. This oxidoreductase protein is encoded by the gene EPX, expressed within these myeloid cells. EPO shares many similarities with its orthologous peroxidases, myeloperoxidase (MPO), lactoperoxidase (LPO), and thyroid peroxidase (TPO). The protein is concentrated in secretory granules within eosinophils. Eosinophil peroxidase is a heme peroxidase, its activities including the oxidation of halide ions to bacteriocidal reactive oxygen species, the cationic disruption of bacterial cell walls, and the post-translational modification of protein amino acid residues.

References

  1. 1 2 Kathiresan M, Martins D, English AM (December 2014). "Respiration triggers heme transfer from cytochrome c peroxidase to catalase in yeast mitochondria". Proceedings of the National Academy of Sciences of the United States of America. 111 (49): 17468–73. Bibcode:2014PNAS..11117468K. doi: 10.1073/pnas.1409692111 . PMC   4267377 . PMID   25422453.
  2. ↑ Martins D, Kathiresan M, English AM (December 2013). "Cytochrome c peroxidase is a mitochondrial heme-based H2O2 sensor that modulates antioxidant defense". Free Radical Biology & Medicine. 65: 541–51. doi:10.1016/j.freeradbiomed.2013.06.037. PMID   23831190.
  3. ↑ Atack JM, Kelly DJ (2007). "Structure, mechanism and physiological roles of bacterial cytochrome c peroxidases". Advances in Microbial Physiology. 52: 73–106. doi:10.1016/S0065-2911(06)52002-8. ISBN   9780120277520. PMID   17027371.
  4. 1 2 Volkov AN, Nicholls P, Worrall JA (November 2011). "The complex of cytochrome c and cytochrome c peroxidase: the end of the road?". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1807 (11): 1482–503. doi: 10.1016/j.bbabio.2011.07.010 . PMID   21820401.
  5. ↑ Guo M, Bhaskar B, Li H, Barrows TP, Poulos TL (April 2004). "Crystal structure and characterization of a cytochrome c peroxidase-cytochrome c site-specific cross-link". Proceedings of the National Academy of Sciences of the United States of America. 101 (16): 5940–5. Bibcode:2004PNAS..101.5940G. doi: 10.1073/pnas.0306708101 . PMC   395902 . PMID   15071191.
  6. ↑ Altchul AM, Abrams R, Hogness TR (1941). "Cytochrome c peroxidase" (PDF). J. Biol. Chem. 136 (3): 777–794. doi: 10.1016/S0021-9258(18)73036-6 .
  7. ↑ Poulos TL, Freer ST, Alden RA, Edwards SL, Skogland U, Takio K, Eriksson B, Xuong N, Yonetani T, Kraut J (January 1980). "The crystal structure of cytochrome c peroxidase" (PDF). The Journal of Biological Chemistry. 255 (2): 575–80. doi: 10.1016/S0021-9258(19)86214-2 . PMID   6243281.
  8. ↑ Yonetani T (1970). "Cytochromec Peroxidase". Cytochrome c peroxidase. Advances in Enzymology and Related Areas of Molecular Biology. Vol. 33. pp. 309–35. doi:10.1002/9780470122785.ch6. ISBN   9780470122785. PMID   4318313.
  9. ↑ Sivaraja M, Goodin DB, Smith M, Hoffman BM (August 1989). "Identification by ENDOR of Trp191 as the free-radical site in cytochrome c peroxidase compound ES". Science. 245 (4919): 738–40. Bibcode:1989Sci...245..738S. doi:10.1126/science.2549632. PMID   2549632.
  10. ↑ Ellfolk N (1967). "Cytochrome c peroxidase. 3. The amino acid composition of cytochrome c peroxidase of Baker's yeast". Acta Chemica Scandinavica. 21 (10): 2736–42. doi: 10.3891/acta.chem.scand.21-2736 . PMID   5585683.
  11. ↑ Iffland A, Tafelmeyer P, Saudan C, Johnsson K (September 2000). "Directed molecular evolution of cytochrome c peroxidase". Biochemistry. 39 (35): 10790–8. doi:10.1021/bi001121e. PMID   10978164.
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