Characterisation of acid proteases from a fusant F76 and its progenitors Aspergillus oryzae HN3042 and Aspergillus niger CICC2377 |
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Authors: | Defeng Xu Caihong Li Yaling Wang Lijun Sun Haifeng Zhao Mouming Zhao |
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Affiliation: | 1. Department of Food Quality and Safety, Guangdong Ocean University, , Zhanjiang, 524088 China;2. Institute of Biochemistry and Molecular Biology of Guangdong Medical College, , Dongguan, 523808 China;3. College of Light Industry and Food sciences, South China University of Technology, , Guangzhou, 510641 China |
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Abstract: | The characteristics of a novel acid protease from a fusant F76 were comparatively evaluated with those from its progenitors Aspergillus oryzae HN3042 and A. niger CICC2377. The UV spectra of these three acid proteases were similar, but fluorescence spectra were different. The acid protease from F76 contained 7.1% α‐helix, 39.4% β‐sheet, 24.7% β‐turn and 32% aperiodic coil, unlike those from its progenitors. The acid protease from F76 was active in the temperature range of 35–55 °C with the optimum temperature of 40 °C and was stable in the pH range of 2.5–6.5 with the optimum pH of 3.5, while those values from A. oryzae HN3042 and A. niger CICC2377 were 45 °C, 4.0 and 40 °C, 3.5, respectively. The kinetic parameters of the acid protease from F76 were different from its progenitors and the Michaelis constant, maximum velocity, activation energy, and attenuation index were 0.96 mg mL?1, 135.14 μmol min?1 mg?1, 64.11 kJ mol?1 and 0.59, respectively. |
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Keywords: | Acid protease enzyme characterisation enzyme kinetic |
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