Cytochrome b5 reductase
Encyclopedia
Cytochrome-b5 reductase (also known as methemoglobin reductase) is a NADH-dependent enzyme
that converts methemoglobin to hemoglobin
. It contains FAD
and catalyzes the reaction:
NADH + H+ + 2 ferricytochrome b5 = NAD+ + 2 ferrocytochrome b5
The following four human genes encode cytochrome-b5 reductases:
entry for CBR
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
that converts methemoglobin to hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...
. It contains FAD
FAD
In biochemistry, flavin adenine dinucleotide is a redox cofactor involved in several important reactions in metabolism. FAD can exist in two different redox states, which it converts between by accepting or donating electrons. The molecule consists of a riboflavin moiety bound to the phosphate...
and catalyzes the reaction:
NADH + H+ + 2 ferricytochrome b5 = NAD+ + 2 ferrocytochrome b5
The following four human genes encode cytochrome-b5 reductases:
- CYB5R1CYB5R1NADH-cytochrome b5 reductase 1 is an enzyme that in humans is encoded by the CYB5R1 gene.-Further reading:...
- CYB5R2CYB5R2Cytochrome b5 reductase 2 is an enzyme that in humans is encoded by the CYB5R2 gene....
- CYB5R3CYB5R3NADH-cytochrome b5 reductase 3 is an enzyme that in humans is encoded by the CYB5R3 gene.-Further reading:...
- CYB5R4CYB5R4Cytochrome b5 reductase 4 is an enzyme that in humans is encoded by the CYB5R4 gene.-Further reading:...
External links
- crystal structure of rat CBR complexed with NAD - crystal structure of pig liver CBR - crystal structure of human erythrocyte CBR - InterProInterPro
InterPro is a database of protein families, domains and functional sites in which identifiable features found in known proteins can be applied to new protein sequences in order to functionally characterise them....
entry for CBR