Investigation on the Activity and Basic Properties of NAGase from Endepidermis of the Green Crab(Scylla serrata)During Different Seasons

The N-Acetyl-β-D-glucosaminidase(NAGase,EC 3.2.1.52) catalyzes the cleavage of N-acetylglucosamine polymers.It is a composition of the chitinases and cooperates with endo-chitinase and exo-chitinase to disintegrate chitinin to N-acetylglucosamine.It is widely distributed in animal tissues and in microorganisms.Green crab is a very typical crustacean for mariculture in China.However,to our best knowledge,no study about tracking detection of chitinolytic enzymes from green crab during different seasons has been reported yet.The variation of activity and basic properties of NAGase from endepidermis of the green crab during different seasons was investigated in this paper.NAGase was extracted with 0.01 mol/L Tris-HCl buffer(pH 7.5) containing 0.2 mol/L NaCl.The results showed that the activities of NAGase from endepidermis exhibited a synchronously evident rhythm.The activity showed a bell-shaped evolution and reached its top value in November.It was found that during different seasons,the optimum pH for this enzyme was 5.6~5.8,and the optimum temperature was 45℃.Besides,the enzyme was stable at pH 5.0~10.0,and below 45 ℃.These results would be useful for cultivation of green crab.