Purification and Characterization of an Extracellular Low Temperature-Active and Alkaline Stable Peptidase from Psychrotrophic Acinetobacter sp. MN 12 MTCC (10786)

An extracellular low temperature-active alkaline stable peptidase from Acinetobacter sp. MN 12 was purified to homogeneity with a purification fold of 9.8. The enzyme exhibited specific activity of 6,540 U/mg protein, with an apparent molecular weight of 35 kDa. The purified enzyme was active over broad range of temperature from 4 to 60 °C with optimum activity at 40 °C. The enzyme retained more than 75 % of activity over a broad range of pH (7.0–11.0) with optimum activity at pH 9.0. The purified peptidase was strongly inhibited by phenylmethylsulfonyl fluoride, giving an indication of serine type. The K _m and V _max for casein and gelatin were 0.3529, 2.03 mg/ml and 294.11, 384.61 μg/ml/min respectively. The peptidase was compatible with surfactants, oxidizing agents and commercial detergents, and effectively removed dried blood stains on cotton fabrics at low temperature ranging from 15 to 35 °C.