Reactive Sulfur Species: Kinetics and Mechanism of the Reaction of Hypothiocyanous Acid with Cyanide To Give Dicyanosulfide in Aqueous Solution
Reactive Sulfur Species: Kinetics and Mechanism of the Reaction of Hypothiocyanous Acid with Cyanide To Give Dicyanosulfide in Aqueous Solution
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DOI：
10.1021/tx900212r
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发表时间：
2009-09-01
影响因子：
4.1
通讯作者：
Ashby, Michael T.
中科院分区：
文献类型：
--
作者：
Lemma, Kelemu;Ashby, Michael T.
人类氰化物(CN-)的主要来源是烟草和职业性烟雾、炎症(髓过氧化物酶(MPO)诱导的甘氨酸氯化)和微生物氰化物(包括囊性纤维化肺的铜绿假单胞菌感染)。健康人的粘膜通常通过包括防御性过氧化物酶系统在内的先天防御机制来保护免受感染。在口腔中，唾液过氧化物酶和MPO催化过氧化氢氧化假卤化物硫氰酸酯(SCN-)生成抗微生物次硫氰酸盐(OSCN-)。乳过氧化物酶在人的肺中进行同样的反应(就像炎症反应中的MPO一样)。在本研究中，我们发现OSCN-和CN-通过二氰基硫化物(NCSCN)与pH相关的动力学反应生成SCN-和氰酸酯(OCN-)，最大速率出现在近中性的生理pH处。除了介绍详细的化学机制外，我们还讨论了尚未解决的问题，包括NCSCN中间体可能的生物学相关性。
The chief sources of cyanide (CN-) in humans are tobacco and occupationally derived smoke, inflammation [vis-h-vis myeloperoxidase (MPO)-induced chlorination of glycine], and microbial cyanogenesis (including Pseudomonas aeruginosa infection of the cystic fibrosis lung). The human mucosae of healthy individuals are usually protected from infection by innate defense mechanisms that include the defensive peroxidase systems. In the oral cavity, salivary peroxidase and MPO catalyze the oxidation of the pseudohalide thiocyanate (SCN-) by hydrogen peroxide to produce the antimicrobal hypothiocyanite (OSCN-). Lactoperoxidase carries out the same reaction in the human lung (as does MPO during inflammatory response). In the present study, we show that OSCN- and CN- react with pH-dependent kinetics to produce SCN- and cyanate (OCN-) via dicyanosulfide (NCSCN), with the maximum rate occuring, near neutral, physiological pH. In addition to presenting it detailed Chemical mechanism, We discuss Unresolved issues, including the possible biological relevance of the NCSCN intermediate.