Stability and structural changes of horseradish peroxidase: Microwave versus conventional heating treatment |
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| Institution: | 1. Department of Biochemistry, Faculty of Science, University of Jeddah, P.O. Box 80203, Jeddah 21589, Saudi Arabia;2. Chemistry Department, Faculty of Applied Science, Taiz University, Taiz, Yemen;3. Department of Chemistry, University College in Al-Jamoum, Umm Al-Qura University, Makkah, Saudi Arabia;1. Textile Research Division, National Research Centre, 33 El Bohouth St., P.O. 12622, Dokki, Giza, Egypt;2. Molecular Biology Department, National Research Centre, 33 El Bohouth St., P.O. 12622, Dokki, Giza, Egypt;3. Electron Microscope and Thin Films Department, Physics Research Division, National Research Centre, 33 El Bohouth St., P.O. 12622, Dokki, Giza, Egypt;4. Medical Molecular Genetics Department, Human Genetics & Genome Research Division, National Research Centre, 33 El Bohouth St., P.O. 12622, Dokki, Giza, Egypt |
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| Abstract: | Effects of conventional heating (CH) and microwave (MW) on the structure and activity of horseradish peroxidase (HRP) in buffer solution were studied. CH incubation between 30 and 45 °C increased activity of HRP, reaching 170% of residual activity (RA) after 4–6 h at 45 °C. CH treatment at 50 and 60 °C caused HRP inactivation: RA was 5.7 and 16.7% after 12 h, respectively. Secondary and tertiary HRP structural changes were analyzed by circular dichroism (CD) and intrinsic fluorescence emission, respectively. Under CH, activation of the enzyme was attributed to conformational changes in secondary and tertiary structures. MW treatment had significant effects on the residual activity of HRP. MW treatment at 45 °C/30 W followed by CH treatment 45 °C regenerated the enzyme activity. The greatest loss in activity occurred at 60 °C/60 W/30 min (RA 16.9%); without recovery of the original activity. The inactivation of MW-treated HRP was related to the loss of tertiary structure, indicating changes around the tryptophan environment. |
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| Keywords: | Horseradish peroxidase Residual activity Conventional heating Microwave Far UV-circular dichroism Tryptophan fluorescence spectroscopy |
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