Redox buffering of hypochlorous acid by thiocyanate in physiologic fluids.
The major antimicrobial products of neutrophilic myeloperoxidase (MPO) in physiologic fluids are hypochlorous acid (HOCl) and hypothiocyanite (OSCN-), and the former is generally believed to be the killing agent. However, we have determined that HOCl oxidizes SCN- in a facile nonenzymic reaction. The observed kinetics and computational models substantiate the hypothesis that SCN- serves to moderate the potential autotoxicity of HOCl by restricting its lifetime in physiologic fluids. Furthermore, the oxidizing equivalents of HOCl are preserved in OSCN-, a more discriminate biocide that is not lethal to mammalian cells.
Ashby
Michael T
MT
Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, Oklahoma 73019, USA. mashby@ou.edu
Carlson
Amy C
AC
Scott
M Jared
MJ
D002021:Buffers; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism; D006997:Hypochlorous Acid / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D013861:Thiocyanates / Q000097:blood / Q000737:chemistry / Q000378:metabolism*
D002021:Buffers; D012709:Serum Albumin; D013861:Thiocyanates; D006997:Hypochlorous Acid; D006861:Hydrogen Peroxide; D009195:Peroxidase