Superoxide, amine buffers and tetranitromethane: a novel free radical chain reaction.
The amine buffer Tris slowly reduces tetranitromethane (TNM) to the nitroform anion in a non-accelerating reaction. The amine buffers HEPES and MOPS also (slowly) react with TNM but the dialkylaminoalkyl radicals formed from these two buffers undergo further reactions resulting in a rapid, accelerating, free radical chain process whereby the amine is oxidized and TNM reduced. The chemical functionality in any reaction component, not necessarily the buffer, required for this radical chain mechanism is >N-CH<. In the presence of such groups, the quantification of superoxide by TNM is impossible.
Hodges
G R
GR
Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario.
Ingold
K U
KU
D000588:Amines / Q000737:chemistry*; D002021:Buffers; D005609:Free Radicals / Q000737:chemistry*; D006531:HEPES; D009025:Morpholines; D010084:Oxidation-Reduction; D013481:Superoxides / Q000737:chemistry*; D013774:Tetranitromethane / Q000737:chemistry*
D000588:Amines; D002021:Buffers; D005609:Free Radicals; D009025:Morpholines; D013481:Superoxides; C008550:morpholinopropane sulfonic acid; D013774:Tetranitromethane; D006531:HEPES