Cytochromes and Related Peptides

Introduction

Cytochrome and related peptides are a kind of electron transfer proteins that use iron porphyrin or heme as a prosthetic group. Common cytochromes and related peptides include cytochrome C and cytochrome P450. Cytochrome C is a type of heme protein widely distributed in organisms, formed by the covalent combination of heme and cytochrome C protein precursor (apocyt C) under the action of the cytochrome C maturation system.

Mechanism of action

Cytochrome C contains many covalently bound heme cofactors. Although the heme binding site on cytochrome C is mostly highly conserved CXXCH (X is any amino acid residue, this site is called a typical site), but there are still some atypical sites, such as CXl5CH (15 random amino acid residues separating two conserved cysteine residues) sites of the sulfate reductase SirA. Cytochrome P450 recognizes substrates through an induction-fit mechanism, which is the key to binding substrates and releasing products.

Application of Cytochromes and Related Peptides

Cytochrome C is a protease extracted from cardiomyocytes of mammals such as pigs and cattle. It plays a role in the transmission of electrons in the process of biooxidation. Cytochrome C is mainly involved as an electron carrier or oxidoreductase in the energy transfer processes of cells such as respiration and photosynthesis. Cytochrome P450 is a ubiquitous heme-containing monooxygenase. It is involved in the synthesis of steroid hormones, the metabolism of fat-soluble vitamins, the conversion of polyunsaturated fatty acids into biologically active molecules, as well as carcinogenesis and drug metabolism. It is mainly used for the first aid of various tissues such as hypoxia (such as cerebral hypoxia, carbon monoxide poisoning and hypoxia caused by heart disease). Abnormal cytochrome P450 leads to mitochondrial dysfunction, apoptosis, and may also be involved in some diseases, such as Parkinson’s disease.

Reference

1. Brown, C. M., Reisfeld, B., & Mayeno, A. N. (2008). Cytochromes P450: a structure-based summary of biotransformations using representative substrates. Drug metabolism reviews, 40(1), 1-100.