Purification and characterization of 29 kDa acid phosphatase from germinating melon seeds

Not much progress on the purification and characterization of low molecular weight acid phosphatases from plants has been made as yet. in the current study a low molecular weight acid phosphatase from seedling of melon was purified about 114-fold with specific activity of 45 u/ mg of protein and a recovery of 3%. the enzyme was found to be homogeneous and showed a single band corresponding to 29 kda on sds-polyacrylamide gel electrophoresis. the km for p -nitrophenyl phosphate was found to be 0.175 mm and vmax was 42 μmol of substrate hydrolyzed /min/mg of protein at ph 5.5 and at 37° c. the enzyme showed its optimum activity at ph 5.0 and 50° c. the enzyme was thermostable and it retained 70% activity for 45 min at 60o c. the ph stability was 4.8-6.0. phosphate,vanadate,molybdate and fluoride acted as strong inhibitors. metal ions such as zn+2,cu+2,ag+1 and hg+2 deactivated the enzyme while other divalent ions such as ca+2 and mg+2 had no effect.