Global Advanced Research Journal of Agricultural Science (GARJAS) ISSN: 2315-5094
June 2016 Vol. 5(6): pp. 175-182
Copyright © 2016 Global Advanced Research Journals
Full Length Research Paper
Isolation, Purification and Characterization of a Thermostable β-Galactosidase isoform from Erythrina indica Seeds
Emadeldin Hassan E. Konozy
Biotechnology Park, Africa City of Technology, Khartoum, B. O. Box: 13332, Sudan
Accepted 06 June, 2016
β-galactosidase (EC 22.214.171.124) is widely distributed in plant tissues and is known to be implicated in hydrolyzing terminal non reducing beta D-galactosyl residues from polysaccharides. 50g Erythrina indica seeds were pulverized and β-galactosidase was extracted and purified in several protein purification steps involved ammonium sulphate fractionation (Am-SO4), gelfiltration, acidification and finally chromatography on cationic ion exchanger. Thus obtained pure enzyme was then characterized with respect to its optimum pH and temperature, effect of metal ions, kinetics parameters and glycoprotein nature. β-galactosidase was purified to apparent electrophoretic homogeneity to 459-fold with comparatively high specific activity (133 Unit/mg). On gelfiltration the estimated native enzyme molecular weight was 66kDa whereas 47 and 32 kDa were obtained for the subunits by SDS-PAGE. The enzyme is a glycoprotein existed in at least three isoforms. It had optimum pH at around 4.5 and 60 oC as favorable temperature at which it was stable for up to 30 minutes. Metals ions like Fe+2, Zn+2, Mg+2, , Mn+2, and Ca+2, had no clear effect on enzyme activity, on the other hand, enzyme activity was fully abolished when incubated with heavy metals like Hg. β-galactosidase had 2.8 and 27 for km and Vmax values, respectively. The purified enzyme exhibited remarkable thermal stability and could, therefore, be good candidate in food industry and biotechnology applications.
Keywords: Erythrina indica; legumanacae; seeds; β-galactosidase isoform; Characterization.