RuBP carboxylase (Rubisco) is the most abundant protein in chloroplasts and probably on earth. It catalyses the carboxylation of ribulose 1-5 biphosphate to form two molecules of 3 phosphoglyceric acid in C3 cycle of photosynthesis. Several types of protein kinase and phosphatases are located to specific subcellular regions. Protein phosphatase-1 (PP-1) is part of that regulatory mechanism it removes phosphates from P-Ser and P-Thr residues of glycogen synthase and phosphorylase kinase reversing the regulatory effect of c-AMP dependent protein kinase. Hexokinase enzyme catalyse the phosphorylation of glucose molecule in glycolysis. Like many other kinases it requires Mg2+ for its activity. The enzymes that degrades DNA rather than synthesis are called nucleases. These may be exonuclease or endonuclease.