phosphorylase

{{Short description|Class of enzymes}}

{{Infobox enzyme

| Name = Phosphorylase

| EC_number = 2.4.1.1

| CAS_number = 9035-74-9

| GO_code =

| image = 1z8d.jpg

| width = 270

| caption =

}}

In biochemistry, phosphorylases are enzymes that catalyze the addition of a phosphate group from an inorganic phosphate (phosphate+hydrogen) to an acceptor.

:A-B + P {{eqm}} A + P-B

They include allosteric enzymes that catalyze the production of glucose-1-phosphate from a glucan such as glycogen, starch or maltodextrin.

Phosphorylase is also a common name used for glycogen phosphorylase in honor of Earl W. Sutherland Jr., who in the late 1930s discovered it as the first phosphorylase.{{cite book | vauthors = Nelson DL, Lehninger AL, Cox MM |title=Lehninger Principles of Biochemistry |date=2005 |publisher=W. H. Freeman |isbn=978-0-7167-4339-2 |page=603 |edition= 5th}}

Function

Phosphorylases should not be confused with phosphatases, which remove phosphate groups.

In more general terms, phosphorylases are enzymes that catalyze the addition of a phosphate group from an inorganic phosphate (phosphate + hydrogen) to an acceptor, not to be confused with a phosphatase (a hydrolase) or a kinase (a phosphotransferase). A phosphatase removes a phosphate group from a donor using water, whereas a kinase transfers a phosphate group from a donor (usually ATP) to an acceptor.

class=wikitable

!Enzyme name

!Enzymes class

!Reaction

!Notes

PhosphorylaseTransferase
(EC 2.4 and EC 2.7.7)
A-B + H-OP {{eqm}} A-OP + H-Btransfer group = A = glycosyl- group or
nucleotidyl- group
'

|Phosphatase

Hydrolase
(EC 3)
P-B + H-OH {{eqm}} P-OH + H-B
KinaseTransferase
(EC 2.7.1-2.7.4)
P-B + H-A {{eqm}} P-A + H-Btransfer group = P
colspan=4|P = phosphonate group, OP = phosphate group, H-OP or P-OH = inorganic phosphate

Types

The phosphorylases fall into the following categories:

All known phosphorylases share catalytic and structural properties.{{cite web | title = PROSITE documentation PDOC00095 [for PROSITE entry PS00102] | url = https://prosite.expasy.org/doc/PS00102 | work = PROSITE }}

Activation

Phosphorylase a is the more active R form of glycogen phosphorylase that is derived from the phosphorylation of the less active R form, phosphorylase b with associated AMP. The inactive T form is either phosphorylated by phosphoylase kinase and inhibited by glucose, or dephosphorylated by phosphoprotein phosphatase with inhibition by ATP and/or glucose 6-phosphate. Phosphorylation requires ATP but dephosphorylation releases free inorganic phosphate ions.

Pathology

Some disorders are related to phosphorylases:

See also

References

{{Reflist}}