title: Characteristics of chemiluminescence observed in the horseradish peroxidase-hydrogen peroxide-tyrosine system.
abstract: Electrolysis or horseradish peroxidase (HRP)-catalyzed oxidation of tyrosine and bityrosine in aqueous solution at pH 7.4 resulted in light emission in the visible region. Electrolysis of tyrosine emitted light which peaked at 490 nm and was almost completely quenched by superoxide dismutase (SOD), while emission by bityrosine peaked at 530 nm. In the HRP-H(2)O(2)-tyrosine system the oxidation-reduction of tyrosine emitted light with two prominent peaks, 490 and 530 nm, and was not quenched by SOD. The phenoxyl neutral radical of the tyrosine in HRP-H(2)O(2)-tyrosine system was detected by electron spin resonance (ESR) spectrometry using tert-nitrosobutane as a spin trap; the spin adduct was found to adhere to the HRP molecule during the enzymatic reaction. Further, bityrosine was detected in the HRP-H(2)O(2)-tyrosine reaction system. Changes in absorption spectra of HRP and chemiluminescence intensities during HRP-catalyzed oxidation of tyrosine suggest that for photon emission compound III is a candidate superoxide donor to the phenoxyl cation radical of tyrosine on the enzyme molecule. The luminescence observed in this study might be originated from at least two exciplexes involved with the tyrosine cation radical (Tyr(*+)) and the bityrosine cation radical (BT(*+))
authors.affiliation: Research Development Corporation Japan, Kojinkai Central Hospital, Sendai, 980-0854, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Totsune
authors.forename: C
authors.initials: C
authors.lastname: Ohno
authors.forename: Y
authors.initials: Y
authors.lastname: Kambayashi
authors.forename: M
authors.initials: M
authors.lastname: Nakano
authors.forename: Y
authors.initials: Y
authors.lastname: Ushijima
authors.forename: S
authors.initials: S
authors.lastname: Tero-Kubota
authors.forename: Y
authors.initials: Y
authors.lastname: Ikegami
mesh_terms: D004572:Electrolysis; D005609:Free Radicals; D006735:Horseradish Peroxidase / Q000737:chemistry / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism*; D008163:Luminescent Measurements; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010636:Phenols; D019810:Sodium Azide / Q000494:pharmacology; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000494:pharmacology; D014443:Tyrosine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005609:Free Radicals; D010636:Phenols; C042329:phenoxy radical; D014443:Tyrosine; D019810:Sodium Azide; D006861:Hydrogen Peroxide; C007543:dityrosine; D006735:Horseradish Peroxidase; D013482:Superoxide Dismutase