Purification, characterization and crystallization of an extracellular alkaline protease from Aspergillus nidulans HA‐10

Abstract

Aspergillus nidulans is a highly potent fungus used in the production of alkaline protease. Extracellular alkaline protease was purified from A. nidulans in a two-step procedure involving ammonium sulphate precipitation and Sephadex G-100 column chromatography. The molecular mass of the enzyme was determined to be 42 kDa by SDS-PAGE. The enzyme activity was also analyzed by zymogram with gelatin. The enzyme was more stable over a wide range of pH (6-10) and the temperatures up to 50 degrees C. It showed optimum enzyme activity at pH 8.0 and a temperature of 35 degrees C. The protease enzyme was completely inhibited by the serine protease inhibitor of phenylmethylsulfonyl fluoride (PMSF). The crystallization of the purified enzyme was performed by hanging drop vapour diffusion method using PEG 6000 as the precipitant. The micro crystals occurred in 40% of PEG 6,000.

Oxidant and solvent stable alkaline protease from Aspergillus flavus and its characterization

“…With regard to pH stability the enzyme was stable between pH range 7.0 to 10.0 and showed 73 and 62% residual activity at pH 11 and 12, respectively. These findings are in accordance with earlier studies (Miyaji et al, 2006), where the optimum pH for alkaline protease was 11-12, whereas, Devi et al (2008) and Charles et al (2008) reported pH optima 10.0 and 8.0, for A. niger and A. niduans HA01, respectively.…”

A novel organic solvent- and detergent-stable serine alkaline protease from Trametes cingulata strain CTM10101

“…1C). Taken together, these observations suggest that SPTC is a monomeric protein comparable to those previously reported for other proteases from fungal strains [21][22][23][24][37][38][39].…”

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