Biochemical studies on α-amylases from Euphorbia tirucalli

Abstract

The quantitative determination of α- amylase activity in latex of E. tirucalii was found to be 2144 units/ml with a specific activity of 131.7 units mg-1 protein, which was a good starting material for preparation of α-amylase. Purification was carried out for the three separated α-amylases namely α–Amylase AI , AII and AIII using columns of DEAE-Sepharose and Sephacryl S-200. Biochemical characterization for α–AmylaseAI which has the highest specific activity with respect of molecular weight (40 kDa), pH optimum (6.0), temperature optimum (50ºC), substrate specificity, Michaelis constant, heat stability, effect of different metal cations and different compounds was carried out. AI is a metaloenzyme; it was activated by Ca2+ (2mM) as the most of plant amylases and therefore it is strongly inhibited by the metal chelatorEDTA, sodium citrate and sodium oxalate.

Key Words: E. tirucalii, α- Amylase, Purification, Characterization, AI, Metaloenzyme.