title: Direct observation of NH2* 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) x 10(9) 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.
authors.affiliation: Chemistry Section, School of Physical and Geographical Sciences, Keele University, Staffs ST5 5BG, UK.
authors.forename: K
authors.initials: K
authors.lastname: Clarke
authors.forename: R
authors.initials: R
authors.lastname: Edge
authors.forename: V
authors.initials: V
authors.lastname: Johnson
authors.forename: E J
authors.initials: EJ
authors.lastname: Land
authors.forename: S
authors.initials: S
authors.lastname: Navaratnam
authors.forename: T G
authors.initials: TG
authors.lastname: Truscott
mesh_terms: D000588:Amines / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry*; D000641:Ammonia / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D008543:Melanins / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011675:Pulse Radiolysis; D013057:Spectrum Analysis
chemical_list: D000588:Amines; D000596:Amino Acids; D008543:Melanins; C016042:phaeomelanin; D017665:Hydroxyl Radical; D000641:Ammonia; D006861:Hydrogen Peroxide; D010100:Oxygen