Abstract: This study was carried out to separate and purify limit dextrinase from malted barley by (NH4)2SO4 salting out, DEAE Sepharose FF column chromatography and Sephadex G-100 column chromatography. A purification fold of 31.23 and a recovery of 8.81% were achieved. The SDS-PAGE pattern of the purified limit dextrinase revealed a single band of protein (97 kD). The effects of temperature and pH on limit dextrinase in both the crude extract and purified sample were studied. The results indicated that maximum activity of the purified limit dextrinase was observed under the conditions of 45 ℃ and pH 5.5 and showed an obvious difference as compared with the crude enzyme extract. Moreover, Mg2+, Ca2+ and Mn2+ increased the activity of the enzyme at low concentrations, whereas Zn2+ and Fe2+ inhibited the activity at high concentrations. K+ did not exhibit any effects on the activity of the enzyme.

Key words: limit dextrinase, purification, enzymatic characterization