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Secondary structure and conformational change of mushroom polyphenol oxidase during thermosonication treatment by using FTIR spectroscopy

Author:
Baltacıoğlu, Hande, Bayındırlı, Alev, Severcan, Feride
Source:
Food chemistry 2017 v.214 pp. 507-514
ISSN:
0308-8146
Subject:
Fourier transform infrared spectroscopy, catechol oxidase, enzyme activity, enzyme inactivation, mushrooms, protein denaturation, temperature, ultrasonic treatment
Abstract:
To understand the conformational changes of mushroom PPO, the secondary structural change of the enzyme during thermosonication treatment at different power (60, 80 and 100%), temperature (20–60°C) and time (0–30min) combinations was investigated by using FTIR spectroscopy and compared with the change in enzyme activity. The enzyme inactivation higher than 99% was obtained at 100% amplitude at 60°C for 10min. FTIR studies showed that marked spectral changes were noted after ultrasound treatment at 20°C. The α-helix and β-sheet contents decreased, while aggregated β-sheet, turns and random coil contents increased as temperature increased up to 60°C during thermosonication treatment for 10min indicating protein denaturation. Aggregated bands located at 1683 and 1616cm−1 became evident after ultrasound treatment at 40°C. When temperature was lowered back to 25°C, from ultrasound treatment at 60°C, these bands were still observed, indicating the irreversible change in the structure.
Agid:
5320402