Free radical inactivation of trypsin |
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| Affiliation: | 1. Department of Infectious Diseases and Neuroinfections, Medical University of Bialystok, Bialystok, Poland;2. Department of Allergy, Guy’s and St Thomas’ Hospital NHS Foundation Trust, London, United Kingdom;1. Department of Biochemistry, Ekiti State University, Ado-Ekiti, Private Mail Bag 5363, Nigeria;2. Department of Biochemistry, Afe Babalola University, Ado-Ekiti, Private Mail Bag 5454, Nigeria;3. Functional Foods and Nutraceuticals Unit, Department of Biochemistry, Federal University of Technology Akure, Private Mail Bag 704, Akure 340001, Nigeria;4. Department of Biomedical Technology, School of Health and Health Technology, Federal University of Technology Akure, Private Mail Bag 704, Akure 340001, Nigeria;2. College of Engineering and Science, Advanced Food Systems Research Unit, Victoria University, Werribee Campus, PO Box 14428, Melbourne, Victoria 8001, Australia |
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| Abstract: | Reactivities of free radical oxidants, .OH, Br-·2 and Cl3COO. and a reductant, CO-·2, with trypsin and reactive protein components were determined by pulse radiolysis of aqueous solutions at pH 7, 20°C. Highly reactive free radicals, .OH, Br-·2 and CO-·2, react with trypsin at diffusion controlled rates, k(.OH + trypsin) = 8.2 × 1010 M-1 s-1, k(Br-·2 + trypsin) = 2.55 × 109 M-1 s-1 and k(CO-·2 + trypsin) = 2.6 × 109 M-1 s-1. Moderately reactive trichloroperoxy radical, k(Cl3COO. + trypsin) = 3 × 108 M-1 s-1, preferentially oxidizes histidine residues. The efficiency of inactivation of trypsin by free radicals is inversely proportional to their reactivity. The yields of inactivation of trypsin by .OH, Br-·2 and CO-·2 are low, G(inactivation) = 0.6-0.8, which corresponds to ∾ 10% of the initially produced radicals. In contrast, Cl3COO. inactivates trypsin with ∾ 50% efficiency, i.e. G(inactivation) = 3.2. |
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