A micellar model for investigating the chemical nature of hydrogen transfer in NAD(P)H-dependent enzymatic reactions
Aqueous micelles of Triton X-100 were shown to catalyse the redox reaction between NADH and 2-p-iodophenyl-3-p-nitrophenyl-5-phenyltetrazolium chloride (INT) at the neutral pH. The transfer of reducing equivalents between the reactants in the micellar system appeared to be direct and quantitative. N...
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Veröffentlicht in: | Biochemical and biophysical research communications 1989-03, Vol.159 (3), p.1330-1336 |
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Sprache: | eng |
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Zusammenfassung: | Aqueous micelles of Triton X-100 were shown to catalyse the redox reaction between NADH and 2-p-iodophenyl-3-p-nitrophenyl-5-phenyltetrazolium chloride (INT) at the neutral pH. The transfer of reducing equivalents between the reactants in the micellar system appeared to be direct and quantitative. N-tert-butylphenyl-α-nitrone, a lipophilic free-radical scavenger which can enter micelles, and superoxide dismutase did not alter the stoichiometry of the reaction. The oxidation product of NADH was found to be 100% enzymatically active. The IR spectrum of INT-formazan (i.e., the product of INT reduction) showed an absorbance at 3,100–3,700 cm
− due to NH-stretching. The presence of NH proton, confirmed further by IH-NMR, together with the above observations suggests that INT, as part of the over-all redox process, abstracts a C(4) hydrogen of the dihydropyridine nucleus of NADH with a simultaneous cleavage at N(2–3) position of its 1,2,3,4-tetrazole ring system and that the redox events are confined to a microenvironment as in the case of NAD(P)H-dependent enzymatic reactions. |
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ISSN: | 0006-291X 1090-2104 |
DOI: | 10.1016/0006-291X(89)92256-0 |