Direct observation of NH2 circle reactions with oxygen, amino acids, and melanins

K. Clarke; R. Edge; V. Johnson; E. J. Land; S. Navaratnam; T. G. Truscott

doi:10.1021/jp076395r

Direct observation of NH2 circle reactions with oxygen, amino acids, and melanins

K. Clarke, R. Edge, V. Johnson, E. J. Land, S. Navaratnam, T. G. Truscott

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Abstract

We report the direct observation of the quenching of the weakly absorbing transient due to the amino radical by oxygen and, hence determine, by a totally direct method, the corresponding rate constant (k = (1.1 ± 0.1) × 109 dm3 mol-1 s-1). We also report the rate constants for the reactions of the amino radical with several amino acids and models of black eumelanin and blond/red phaeomelanin. These reactions lead to a mechanism, based on free radicals, that can explain why ammonia is useful in commercial hair (melanin) bleaching, avoiding excessive amino acid (hair protein) damage.

Original language	English
Pages (from-to)	1234-1237
Journal	Journal of Physical Chemistry A
Volume	112
Issue number	6
DOIs	https://doi.org/10.1021/jp076395r
Publication status	Published - 14 Feb 2008

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title = "Direct observation of NH2 circle reactions with oxygen, amino acids, and melanins",

abstract = "We report the direct observation of the quenching of the weakly absorbing transient due to the amino radical by oxygen and, hence determine, by a totally direct method, the corresponding rate constant (k = (1.1 ± 0.1) × 109 dm3 mol-1 s-1). We also report the rate constants for the reactions of the amino radical with several amino acids and models of black eumelanin and blond/red phaeomelanin. These reactions lead to a mechanism, based on free radicals, that can explain why ammonia is useful in commercial hair (melanin) bleaching, avoiding excessive amino acid (hair protein) damage.",

author = "K. Clarke and R. Edge and V. Johnson and Land, {E. J.} and S. Navaratnam and Truscott, {T. G.}",

year = "2008",

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journal = "Journal of Physical Chemistry A",

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TY - JOUR

T1 - Direct observation of NH2 circle reactions with oxygen, amino acids, and melanins

AU - Clarke, K.

AU - Edge, R.

AU - Johnson, V.

AU - Land, E. J.

AU - Navaratnam, S.

AU - Truscott, T. G.

PY - 2008/2/14

Y1 - 2008/2/14

N2 - We report the direct observation of the quenching of the weakly absorbing transient due to the amino radical by oxygen and, hence determine, by a totally direct method, the corresponding rate constant (k = (1.1 ± 0.1) × 109 dm3 mol-1 s-1). We also report the rate constants for the reactions of the amino radical with several amino acids and models of black eumelanin and blond/red phaeomelanin. These reactions lead to a mechanism, based on free radicals, that can explain why ammonia is useful in commercial hair (melanin) bleaching, avoiding excessive amino acid (hair protein) damage.

AB - We report the direct observation of the quenching of the weakly absorbing transient due to the amino radical by oxygen and, hence determine, by a totally direct method, the corresponding rate constant (k = (1.1 ± 0.1) × 109 dm3 mol-1 s-1). We also report the rate constants for the reactions of the amino radical with several amino acids and models of black eumelanin and blond/red phaeomelanin. These reactions lead to a mechanism, based on free radicals, that can explain why ammonia is useful in commercial hair (melanin) bleaching, avoiding excessive amino acid (hair protein) damage.

U2 - 10.1021/jp076395r

DO - 10.1021/jp076395r

M3 - Article

SN - 1089-5639

VL - 112

SP - 1234

EP - 1237

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

IS - 6

ER -

Direct observation of NH2 circle reactions with oxygen, amino acids, and melanins

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