The Effect of Temperature, pH, and Salt on Amylase in Heliodiaptomus viduus (Gurney) (Crustacea: Copepoda: Calanoida)

Authors : Tapan Kr DUTTA, Malabendu JANA, Priti R PAHARI, Tanmay BHATTACHARYA

Pages : 187-195

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :An interesting a-amylase has been obtained in large quantity insert ignore into journalissuearticles values(2400 U/g of body weight); with specific activity insert ignore into journalissuearticles values(20.22 U/g protein); from a freshwater zooplankton, Heliodiaptomus viduus insert ignore into journalissuearticles values(Gurney);. Partially purified enzyme showed activity up to 70 ºC and demonstrated optimum activity at 30 ºC. The enzyme was active between pH 3.5 and 8.5, with maximum activity at pH 6.0. It retained its full activity at 30 ºC for 2 h, but became inactive at 60 ºC after 2 h, and at 70 ºC after 1 h. Enzyme activity was retained at 60% in 2 M NaCl after 24 h incubation, while full activity was found in 0.5 M NaCl for the same duration of incubation. Addition of metal ions like Fe2+, Ba2+, Co2+, Ag2+, and Mn2+ enhanced activity up to 130%-200% of the original activity, while K+ and Sn2+ caused a negligible increase in the activity. Addition of Hg2+ and Li2+ completely inhibited amylase activity, whereas Cu2+, Mg2+, and Pb2+ reduced activity to as little as 5% of original activity. Soluble starch, amylose, and amylopectin were completely digested by this amylase, whereas glycogen was hydrolyzed to a lesser extent. During hydrolysis of soluble starch, initially, maltose insert ignore into journalissuearticles values(G2); and maltotetraose insert ignore into journalissuearticles values(G4); were produced in similar magnitude, followed by a distinctly higher amount insert ignore into journalissuearticles values(> 80%); of maltose. Amylose was the most potential substrate with a Km value of 1.82 mg/ml. The molecular mass was 50 kDa in the Native PAGE and no multiple forms were observed.
Keywords : Heliodiaptomus viduus, calanoid copepod, zooplankton, amylase