Phosphorylase

About Phosphorylases:

Phosphorylases are best known as the enzymes that are responsible for catalyzing an addition for a phosphate group. This occurs from a phosphate which is inorganic to a potential acceptor.
The reaction is known as: A - B + P = P-B
The phosphorylases do include a range of allosteric enzymes that are responsible for catalyzing the production from glycogen to glucose-1-phosphate. This includes everything from starch to glycogen and maltodextrin. The name is also often used instead of glycogen phosphorylase.

Phosphorylases Mechanism
Phosphorylase is more the typical active R form for glycogen phosphorylase. This is taken from a less active R form known as phosphorylation which is phosphorylase b. This is also associated with AMP. Then there is also the T form to consider. This can be inhibited through glucose as well as being phosphorylated by phosphorylase kinase. Alternatively, it could be dephosphorylated through the phosphoprotein. This is achieved through the inhibition of ATP or potentially the glucose 6 phosphate
To achieve phosphorylation, it is necessary to require ATP. When this does occur through the process of dephosphorylation, phosphate ions which are inorganic will then be released.

Phosphorylases Interactions
There are certain disorders that are related to phosphorylases. This does include both glycogen storage disease type V as well as glycogen storage disease type VI. These are muscle glycogens and live glycogens respectively.

Phosphorylases Function
It’s important to make sure that you don’t confuse phosphorylases with phosphatases. This is a common mistake but these are actually responsible for the removal of phosphate groups. To better understand phosphorylates, one must consider the function. This is best described as enzymes that are used to catalyze an additional group from an inorganic phosphate towards an acceptor. This is not the same as a kinase or a phosphatase.
A kinase will transfer a phosphate group from the area of a donor towards a receptor. In contrast, a phosphate relocates the phosphate group using water.

Phosphorylases Structure
This is a large protein. It is actually comprised of 842 amino acids in total. As well as this, it does have a mass of 97.434 kDa. It is possible for the enzyme to exist in the form of a tetramer or an inactive monomer. However, it will be biologically active when in the form of a dimer and when there are two completely identical subunits.
In mammals, these can be found in a variety of places, including the liver, brain, and muscle. When found in the brain, it will typically occur in adults while it can also be discovered in the adult skeletal muscle and liver as well. There is a range of different regions of the enzyme which are particularly biologically significant. This does include, binding sites, allosteric sites, as well as a completely reversible, phosphorylate serine residue to name just a few areas.
It is particularly significant to note the fact that catalytic sites are relatively buried. This makes access to the site from the surface of the structure incredibly difficult.