Module 2 : ENZYMES IN GENETIC ENGINEERING

Lecture 3 : Enzymes in Modification- Phosphatases and Methylases and their Mechanism of Action

 

2-3.1 Phosphatase:

•  Phosphatase catalyses the cleavage of a phosphate (PO4-2) group from substrate by using a water molecule (hydrolytic cleavage).

•  This reaction is not reversible.

•  This shows totally opposite activity from enzyme like kinase and phosphorylase that add a phosphate group to their substrate. On the basis of their activity there are two types of phosphatase i.e acid phosphatase and alkaline phosphatase. In both forms the alkaline phosphatase are most common.

•  Special class of phosphatase that remove a phosphate group from protein, called “Phosphoprotein phosphatase”.

Fig 2-3.1: Schematic representation of hydrolytic cleavage of phosphate group (PO4-2).


2-3.1.1 Acid phosphatase :

•  It shows its optimal activity at pH between 3 and 6, e.g. a lysosomal enzyme that hydrolyze organic phosphates liberating one or more phosphate groups. They are found in prostatic epithelial cells, erythrocyte, prostatic tissue, spleen, kidney etc.