What does cytochrome b5 do?

Cytochrome b5 reductase is an enzyme in the blood. It controls the amount of iron in your red blood cells, and helps the cells carry the normal amount of oxygen. Persons who do not have enough of this enzyme may develop a condition called methemoglobinemia.

What is the function of cytochrome enzymes?

Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions 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.

What is cytochrome P450?

The superfamily of proteins called cytochrome P450 (CYP) enzymes are involved in the synthesis and metabolism of a range of internal and external cellular components. These enzymes have been identified in many organisms, including animals, plants, bacteria, and even in a few viruses.

Is cytochrome b5 an enzyme?

CAS no. In its b5-reducing capacity, this enzyme is involved in desaturation and elongation of fatty acids, cholesterol biosynthesis, and drug metabolism. This enzyme can also reduce methemoglobin to normal hemoglobin, gaining it the inaccurate synonym methemoglobin reductase.

Is cytochrome a C?

Cytochrome c is a heme protein that is localized in the compartment between the inner and outer mitochondrial membranes where it functions to transfer electrons between complex III and complex IV of the respiratory chain.

How do cytochromes work?

Cytochrome, any of a group of hemoprotein cell components that, by readily undergoing reduction and oxidation (gain and loss of electrons) with the aid of enzymes, serve a vital function in the transfer of energy within cells. Hemoproteins are proteins linked to a nonprotein, iron-bearing component.

What inhibits CYP450?

Cytochrome P450 enzymes can be inhibited or induced by drugs, resulting in clinically significant drug-drug interactions that can cause unanticipated adverse reactions or therapeutic failures. Interactions with warfarin, antidepressants, antiepileptic drugs, and statins often involve the cytochrome P450 enzymes.

Why is cytochrome c red?

Like many proteins that carry electrons, it contains a special prosthetic group that handles the slippery electrons. Cytochrome c contains a heme group with an iron ion gripped tightly inside, colored red here. The iron ion readily accepts and releases an electron.

What happens if cytochrome c is inhibited?

Cyanide, azide, and carbon monoxide all bind to cytochrome c oxidase, inhibiting the protein from functioning and leading to the chemical asphyxiation of cells. NO and CN− will compete with oxygen to bind at the site, reducing the rate of cellular respiration.

What is the basic structure of cytochromes?

Cytochromes are redox-active proteins containing a heme, with a central Fe atom at its core, as a cofactor. They are involved in electron transport chain and redox catalysis. They are classified according to the type of heme and its mode of binding.

What is a CYP450 inducer?

CYP enzyme inducers increase the rate of hepatic metabolism, usually through increased transcription of mRNA, and decrease serum concentrations of other drugs metabolized by the same hepatic isoenzyme.

What is the role of cytochrome b 5 in the hemoprotein?

Although most indications of interactions between cytochrome P450 and cytochrome b 5 suggest an electron transfer role for the latter hemoprotein, it has also been proposed that the cytochrome b 5 might serve in a nonelectron transfer role as an effector Hlavica (1984), Lipscomb et al (1976), Loughran et al (2001).

How does cytochrome b5 stimulate the reductase?

As shown in the scheme, cytochrome b 5 stimulates input of the first electron from the reductase as well as product formation. The detailed mechanism of enhanced product formation is still to be elucidated, as are the mechanisms of the structural effects. Fig. 4..

What does cytochrome b 5 do in the monooxygenase reaction?

In this capacity, the cytochrome b 5 could be acting as an allosteric activator of some aspect of the monooxygenase reaction, perhaps enhancing electron transfer through the system (although not through itself), or perhaps stabilizing the oxygenated cytochrome P450 against uncoupling.

Is the cytochrome b5 required for arachidonic acid metabolism?

CYP4A7 has an obligate requirement for cytochrome b 5 in arachidonic acid metabolism. The NADPH-cytochrome P450 reductase-supported metabolism of myristic acid or lauric acid by this hemoprotein is not obligatory for cytochrome b 5, but is stimulated by it.