Question

What is the difference between a a reaction that is catalyzed by a kinase compared to one that is catalyzed by a phosphorylase? (Describe the various roles/mechanisms of each, utilization of ATP, etc).

Answer 1

Kinase and phosphorylase both add phosphate group to a particular substance and play important role in the regulation of cell processes.

Kinase:

• Kinase add phosphate group to a particular enzyme by taking phosphate group from high energy compound like ATP and transfer phosphate group from ATP to substrate without breaking the bonds in substrate.
• It mainly add phosphate group to organic substrates like lipid, protein, carbohydrate and nucleic acid.
• Generally regulated by phosphorylation.
• Example Protein kinase, lipid kinase, carbohydrate kinase.

Phosphorylase:

• Phosphorylase add phosphate group to organic compounds by taking phosphate from inorganic compound. It does not involve ATP and main difference is that it add phosphate group by breaking bonds between substrate and monomer.
• Add phosphate group to the organic componds like glucose.
• Generally regulated by eitther allosteric regulation or phosphorylation.
• examples are glycogen phosphorylase, starch phosphorylase.