Nickelsen M G, Nweke A, Scully F E, Ringhand H P
Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia 23529-0126.
Chem Res Toxicol. 1991 Jan-Feb;4(1):94-101. doi: 10.1021/tx00019a013.
Aqueous chlorine reacts with tyrosine to form ring-chlorinated products. Ring substitution occurs at Cl:tyrosine mole ratios greater than 1. Because the nitrogen function of amides is much less reactive than that of amines, the aromatic ring of N-acetyltyrosine is chlorinated at chlorine:substrate mole ratios less than 1. When an aqueous solution of the gastric protein pepsin was chlorinated (37 degrees C, 45 min), tyrosine residues were chlorinated at pH 2 but not at pH 8. The carbohydrate, protein, and chloride concentrations in stomach fluid from fasted rats were determined. When varying concentrations of aqueous chlorine (20-180 mg/L Cl2) were added to the stomach fluid at pH 2, tyrosine residues were mono- and dichlorinated on the aromatic ring. The amount of mono- to dichlorination products varied with the concentration of aqueous chlorine. A mechanism is proposed. The implications for toxicological studies involving chlorinated drinking water are discussed.
氯水与酪氨酸反应生成环氯化产物。当氯与酪氨酸的摩尔比大于1时会发生环取代反应。由于酰胺的氮官能团的反应活性远低于胺，在氯与底物的摩尔比小于1时，N - 乙酰酪氨酸的芳香环会被氯化。当对胃蛋白酶的水溶液进行氯化（37摄氏度，45分钟）时，酪氨酸残基在pH值为2时被氯化，而在pH值为8时则不会。测定了禁食大鼠胃液中的碳水化合物、蛋白质和氯化物浓度。当在pH值为2的胃液中加入不同浓度的氯水（20 - 180毫克/升Cl₂）时，酪氨酸残基在芳香环上发生单氯代和二氯代反应。单氯代和二氯代产物的量随氯水浓度而变化。提出了一种机制。讨论了其对涉及氯化饮用水的毒理学研究的影响。
