Purification and properties of α-amylase from Micrococcus varians

An extracellular α-amylase from Micrococcus varians was partially purified (63 fold) by ammonium sulphate precipitation followed by dialysis and separated by molecular exclusion into three components with molecular weights ranging from approximately 14,000 to 56,000. The amylase had a pH optimum of 7.0 and apparent Km of approximately 0.5 mg ml^-1 for starch. The enzyme activity was stimulated by Ca²⁺ and Mg²⁺ ions. Optimum temperature was 45 °C while there was a complete absence of activity at 70 °C in 20 min. Ethylene diaminetetra acetic acid (EDTA) and iodoacetic acid (IA) inhibited the activity of the enzyme.