EXTRACTION AND PURIFICATION OF Β-GALACTOSIDASE FROM (ZIZIPHUS SPINA-CHRISTI)

Abstract

β-galactosidase enzyme EC (3.2.1.23), lactase, can be described as an enzyme of glycoside hydrolase which performs the catalyzing of β-galactosides hydrolysis to mono-saccharides by breaking glycosidic bond. The objective of this study was to extraction and purification β-galactosidase from (Ziziphus spina-christi.), ten Different types of extraction were investigated to selection of the best extraction of the enzyme, The Na. phosphate buffer (0.2M and pH6) had given a highest Specific activity of crude enzyme has been 101.36 U/mg. protein. The purification procedures were performed with the use of the precipitation of ammonium sulfate, ion-exchange and gel filtration chromatographic techniques. 70% ammonium sulfate saturation has been the best method for precipitation and partially purification of enzyme with a purification fold 1.34 and enzymatic yield 63.90%. This was followed by the use of ion exchange chromatography by DEAE Sephadex A50 column, the purification times of the enzymatic extract were 2.66, with an enzymatic yield 31.52%. After the final purification step of gel filtration chromatography using SephadexG-100 column, the enzyme has been purified 4.12 fold with 21.91% of enzymatic yield. The optimum enzymatic activity was found at pH 6. The enzyme’s molecular weight has been estimated to 77.53 KD by the gel filtration chromatography method, and 75 kD on SDS-PAGE.