Purification and Characterization of α and β- Amylases Isolated from Millet ( Pennisetum glaucum ) Malt

Abstract

The work aimed to study the diastatic power (PD) of millet malt, to purify the α and β – amylases and to characterize these enzymes. In this study the amylolytic activity initiated during the germination of millet was determined. Fourth day of germination of millet grains showed the highest of the amount of diastatic power (DP) (54.00 IOB), no significant variation (P≤ 0.05) between the extraction procedures followed either by distilled water or water with 2% peptone. DEAE-cellulose chromatography was used for the partial purification of α-and β-amylases. The results obtained from the last purification steps is 6.5o fold of α-amylase in fifth day of germination, whereas β-amylase is 37.50 fold in fourth day of germination. These amylases isolated from millet malt have interesting characteristics such as, storage stability of purified α and β-amylases at different temperature (-20 and 4ºC) for 56 days. No significant loss (P≤0.05) in the enzymes activity during the storage period for 56 days in -20ºC, whereas the loss of enzyme activity at 4ºC during the period of 56 days were 28% for α and 35% for β-amylases. The maximum activity of α-amylase was obtained at temperature 70ºC and 50ºC for β-amylase, it was clear that the α –amylase is more stable than β-amylase. The optimum pH for both α and β-amylases were 5.0 and 5.5 respectively. Therefore, these characterizations meet the prerequisites need for food industry. This work contributed with the advances in biotechnology generating of conditions for application of a new and of low price amylases source.