Inactivation mechanism of polyphenol oxidase during ultrasound treatment

Download

index.pdf

Date

2014

Author

Baltacıoğlu, Hande

Metadata

Show full item record

Item Usage Stats

200
views

101
downloads

In this study, the activity and conformational changes of mushroom polyphenol oxidase (PPO) were investigated during the inactivation by heat-ultrasound treatment at different power, temperature and time combinations. The secondary structure change of the enzyme during inactivation was analyzed by using Fourier Transform Infrared (FTIR) spectroscopy and compared with the enzyme activity change. In thermosonication (TS) treatment, the residual enzyme activity decreased with increasing power, time and temperature. The enzyme inactivation higher than 99 % was obtained at 100 % amplitude at 60 °C for 10 min. For comparison, when the stability of mushroom PPO after thermal treatment was investigated, approximately 99% inactivation was obtained at 70 °C for 5 min. D value for thermal treatment at 60°C was found as 6.66 min whereas for 100, 80 and 60 % amplitude TS treatments at the same temperature, D values were found as 2.09, 3.33 and 3.44 min, respectively. FTIR studies showed that the thermal and TS treatments caused an irreversible change on the secondary structure of the enzyme. α-helix and β-sheet content decreased, while aggregated β-sheet, turns and random coil content increased during the temperature increase. The transition temperature (Tm) values of TS and thermal treatments were 44 and 55 ºC, respectively. This result showed that heat and ultrasound combination behaved synergistically on the conformational change of the enzyme. Compared to the thermal treatment, TS treatment seemed to be more effective on the secondary structural change at lower temperatures.

Subject Keywords

Polyphenol oxidase., Proteins., Enzyme activation., Fourier transform infrared spectroscopy.

URI

http://etd.lib.metu.edu.tr/upload/12617347/index.pdf
https://hdl.handle.net/11511/23583

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Polifenol oksidaz enziminin ısı-ultrason kombinasyonu ile inaktivasyonu sırasında enzimin yapısında meydana gelen değişimin fourier değişim kızıl ötesi (FTIR) spektroskopisi ile incelenmesi Baltacıoğlu, Hande; Bayındırlı, Alev(2013) This project was related to understand the conformational changes of PPO after inactivation by heat and heat-ultrasound at different power, temperature and time combinations. The secondary structure change was analyzed by using FTIR spectroscopy and compared with the change in the enzyme activity. When stability of mushroom PPO after heat treatment was investigated, the enzyme remained fully active up to 40oC. There was a slight decrease during the period of 30 min at 40°C; between 50oC and 70°C higher inac...
Secondary structure and conformational change of mushroom polyphenol oxidase during thermosonication treatment by using FTIR spectroscopy Baltacıoğlu, Hande; Bayındırlı, Alev; Severcan, Feride (2017-01-01) 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 degrees C) and time (0-30 min) 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 degrees C for 10 min. FTIR studies showed that marked spectral changes were noted after ultrasound trea...
Biophysical characterization of proteins in solution and human fluids for cancer diagnosis applications using fourier transform infrared spectroscopy Abbas, Sherif Abbas Mousa; Severcan, Feride; Severcan, Mete; Department of Biology (2016) Proteins play very important roles in cells regulation and structure. Understanding of proteins structures greatly help in understanding of the mechanism of action of these proteins. The optical spectroscopic techniques such as Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy can be used to study proteins in its native environment without complicated sample preparations that is required for a high resolution technique such as x-ray. In order to calculate the protein secondary struc...
Immobilization of glucose oxidase in poly(2-hydroxyethyl methacrylate) membranes Arica, Y.; Hasirci, V.N.; Arica, Yakup (Elsevier BV, 1987-11) Glucose oxidase (GOD) was immobilized in a poly(2-hydroxyethyl methacrylate) (HEMA) membrane through matrix entrapment in order to investigate the effect of various parameters (e.g. concentration of ingredients, temperature, repeated interaction with glucose and shelf storage) on the activity of the enzyme. Permeability of the membrane to a model permeant was tested and SEMs were obtained. It was observed that upon immobilization the affinity of GOD towards glucose was substantially decreased, and increasin...
ATR-FTIR evaluation of structural and functional changes on murine macrophage cells upon activation and suppression by immunotherapeutic oligodeoxynucleotides Spahiu, Emrulla; Severcan, Feride; Gürsel, Mayda; Department of Biology (2015) In the present study, ATR-FTIR was used to examine the structural and functional changes on murine macrophage cells upon activation and suppression by immunotherapeutic ODNs. Macrophage cells play a key role in innate and adaptive immunity. Their possession of high flexibility helps them to successfully respond to environmental signals. In this context, they can impressively alter their physiology in relation to their function and these changes have large molecular signals in the infrared spectral region th...

Citation Formats

H. Baltacıoğlu, “Inactivation mechanism of polyphenol oxidase during ultrasound treatment,” Ph.D. - Doctoral Program, Middle East Technical University, 2014.