INT (iodonitrotetrazolium or 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2''H''-tetrazolium) is a commonly used tetrazolium salt (usually prepared with chloride ions), similar to
tetrazolium chloride
Triphenyl tetrazolium chloride (TTC), or simply tetrazolium chloride (with the formula 2,3,5-triphenyl-2H-tetrazolium chloride) is a redox indicator commonly used in biochemical experiments especially to indicate cellular respiration. It is a wh ...
that on reduction produces a red
formazan
The formazans are compounds of the general formula -N=N-C(R')=N-NH-R" formally derivatives of formazan 2NN=CHN=NH unknown in free form.
Formazan dyes are artificial Chromogen, chromogenic products obtained by reduction of tetrazolium salts ...
dye that can be used for quantitative redox
assay
An assay is an investigative (analytic) procedure in laboratory medicine, mining, pharmacology, environmental biology and molecular biology for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity ...
s. It is also toxic to prokaryotes.
INT is an artificial
electron acceptor
An electron acceptor is a chemical entity that accepts electrons transferred to it from another compound. Electron acceptors are oxidizing agents.
The electron accepting power of an electron acceptor is measured by its redox potential.
In the ...
that can be utilized in a
colorimetric assay to determine the concentration of
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
in a solution. It can be reduced by
succinate dehydrogenase
Succinate dehydrogenase (SDH) or succinate-coenzyme Q reductase (SQR) or respiratory complex II is an enzyme complex, found in many bacterial cells and in the inner mitochondrial membrane of eukaryotes. It is the only enzyme that participates ...
to furazan, the formation of which can be measured by absorbance at 490
nm. The activity of succinate dehydrogenase is readily observed by the naked eye as the solution turns from colorless to rusty red.
See also
*
MTT assay
The MTT assay is a colorimetric assay for assessing cell metabolic activity. NAD(P)H-dependent cellular oxidoreductase enzymes may, under defined conditions, reflect the number of viable cells present. These enzymes are capable of reducing the t ...
References
Biochemistry detection reactions
Chlorides
Dyes
Electrochemistry
Redox indicators
Tetrazoles
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