| Autor: |
Choe JK; Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305, United States., Richards DH; Department of Chemical and Environmental Engineering, Yale University , New Haven, Connecticut 06520, United States., Wilson CJ; Department of Chemical and Environmental Engineering, Yale University , New Haven, Connecticut 06520, United States., Mitch WA; Department of Civil and Environmental Engineering, Stanford University , Stanford, California 94305, United States. |
| Jazyk: |
angličtina |
| Zdroj: |
Environmental science & technology [Environ Sci Technol] 2015 Nov 17; Vol. 49 (22), pp. 13331-9. Date of Electronic Publication: 2015 Nov 02. |
| DOI: |
10.1021/acs.est.5b03813 |
| Abstrakt: |
Proteins are important targets of chemical disinfectants. To improve the understanding of disinfectant-protein reactions, this study characterized the disinfectant:protein molar ratios at which 50% degradation of oxidizable amino acids (i.e., Met, Tyr, Trp, His, Lys) and structure were observed during HOCl, HOBr, and O3 treatment of three well-characterized model proteins and bacteriophage MS2. A critical question is the extent to which the targeting of amino acids is driven by their disinfectant rate constants rather than their geometrical arrangement. Across the model proteins and bacteriophage MS2 (coat protein), differing widely in structure, methionine was preferentially targeted, forming predominantly methionine sulfoxide. This targeting concurs with its high disinfectant rate constants and supports its hypothesized role as a sacrificial antioxidant. Despite higher HOCl and HOBr rate constants with histidine and lysine than for tyrosine, tyrosine generally was degraded in preference to histidine, and to a lesser extent, lysine. These results concur with the prevalence of geometrical motifs featuring histidines or lysines near tyrosines, facilitating histidine and lysine regeneration upon Cl[+1] transfer from their chloramines to tyrosines. Lysine nitrile formation occurred at or above oxidant doses where 3,5-dihalotyrosine products began to degrade. For O3, which lacks a similar oxidant transfer pathway, histidine, tyrosine, and lysine degradation followed their relative O3 rate constants. Except for its low reactivity with lysine, the O3 doses required to degrade amino acids were as low as or lower than for HOCl or HOBr, indicating its oxidative efficiency. Loss of structure did not correlate with loss of particular amino acids, suggesting the need to characterize the oxidation of specific geometric motifs to understand structural degradation. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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