Characterization of membrane-bound polyphenol oxidase from Granny Smith apple (Malus × domestica Borkh.)

• Published in: International journal of biological macromolecules 2020-09, Vol.158, p.977-984
• Main Authors: Han, Qianyun, Liu, Fang, Hao, Yanling, Ni, Yuanying
• Format: Article
• Language: English
• Subjects: Characterization; Enzyme activity; Membrane-bound polyphenol oxidase; Molecular properties
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2020.04.225

Membrane-bound polyphenol oxidase (mPPO) from the Granny Smith apple was purified and characterized. The enzyme was purified by a factor of 20.53 with a recovery of 1.8%. The molecular weight of purified mPPO was determined to be 65 kDa by electrophoresis and nano-electrospray ionization mass spectrometry. mPPO exhibited its highest activity at a temperature of 35 °C and a pH of 7.0 and can be regarded as a diphenol oxidase. A low concentration of SDS (≤0.5 mM) enhanced the enzymatic activity, whereas mPPO was activated at high concentration EDTA (≥2 mM). The thermal transition temperature of mPPO was 76.98 °C. The circular dichroism spectrum showed that mPPO contains high α-helix content, the fluorescence spectroscopy indicated that the tryptophan residues of mPPO are partially buried. The particle size of mPPO was 5–10 nm with a complete structure. The structural characterization of mPPO provided better insights into the regions responsible for its activity. •mPPO was monomeric with a molecular weight of approximately 65 kDa.•mPPO was more resistant to high temperature compared to PPO from other sources.•mPPO was present in its latent form and can be activated by EDTA.•The characterization of mPPO provided support for the storage of apple-based products.