Purification and kinetic properties of a novel β-amylase from Penicillum citrinum AS-9

Document Type : Original Article

Authors

1 Chemistry of Natural and Microbial Products Dept., Pharmaceutical and Drug Industries Research Div.National Research Centre, Dokki, Giza, Egypt P.O. Box: 12622

2 Dept. of Biological and Geological Sciences, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt

3 National Resesrch Centre

4 Dept. of Biological and Geological Sciences, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt.

Abstract

β-amylase-rich preparation produced by the soil fungal strain Penicillium citrinum AS-9 was completely purified within the succeeding steps; ultrafiltration, acetone fractionation and gel filtration on Sephadex G-150 column. Acetone fractionation recovered the highest β-amylase activity and the 85% acetone fraction exhibited 3.5-fold activity that of the crude enzyme. The column affected 8.6-fold purification for β-amylase, which produced maltose as the major product of starch hydrolysis. The pure enzyme showed a Km value of 17.5 mM and Vmax of 17.5 Umg-1 protein, applying Woolf plot and exhibited its maximum velocity at pH 7.1 and 50°C. In absence of substrate, thermal treatments of the enzyme solution at pH 5.2 and 5.5 had the most adverse effects on the enzyme activity. CaCl2 (1mM) activated the enzyme, while each of Ca2+, Fe3+, cysteine, cystine, I2 and p-chloromercuribenzoate (PCMB) had different inhibitory effects. Maltose as the enzyme product at final concentration of 80 mM strongly inhibited the enzyme.

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History

  • Receive Date: 15 September 2021
  • Revise Date: 26 September 2021
  • Accept Date: 03 October 2021

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