title: Secondary structure and conformational change of mushroom polyphenol oxidase during thermosonication treatment by using FTIR spectroscopy.
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.
authors: Department of Food Engineering, Niğde University, 51240 Niğde, Turkey; Department of Food Engineering, Middle East Technical University, 06800 Ankara, Turkey.
authors: Hande
authors: H
authors: Baltacıoğlu
authors: Department of Food Engineering, Middle East Technical University, 06800 Ankara, Turkey.
authors: Alev
authors: A
authors: Bayındırlı
authors: Department of Biological Sciences, Middle East Technical University, 06800 Ankara, Turkey. Electronic address: feride@metu.edu.tr.
authors: Feride
authors: F
authors: Severcan
mesh_terms: D000363:Agaricales / Q000737:chemistry / Q000201:enzymology*; D004156:Catechol Oxidase / Q000737:chemistry*; D006358:Hot Temperature; D010940:Plant Proteins / Q000737:chemistry*; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D014465:Ultrasonics; D014675:Vegetables / Q000737:chemistry / Q000201:enzymology
chemical_list: D010940:Plant Proteins; D004156:Catechol Oxidase
keywords: Conformation change; FTIR; PPO; Protein secondary structure; Spectroscopy; Thermosonication