Reduction of Cu(II) complexes of histidine and histidyl peptides. A pulse radiolysis study. [Electrons]
The reduction mechanism of Cu(II) complexes of histidine and histidyl peptides was investigated using the pulse radiolysis method. The hydrated electron, used as a reducing agent, was found to react with the complexes by a bimolecular process. In the Cu(II)-histidine and Cu(II)-glycyl-histidine complexes at pH 11, the reaction with the e/sub aq//sup -/ is direct with the Cu(II) ion and no secondary reactions were found to occur up to 5 msec after the pulse. In the Cu(II)-glycyl-histidine complex at pH 6.5 and Cu(II)-..beta..-alanyl-histidine at pH 7.5, the decay of the electron was followed by the appearance of a transient absorption band centered at 360 nm. This band is assigned to the adduct of an electron in the imidazole ring of the histidyl peptides. The radical ion is formed by the direct reaction of the e/sub aq//sup -/ with the liganded histidyl residue. The Im decays via a first order process at the same rate at which the Cu(II) ion is reduced. CO/sub 2//sup -/ reduces all the complexes studied via a bimolecular reaction. It is suggested that this is a direct reaction of the CO/sub 2//sup -/with the metal ion. An attempt to correlate these reaction steps to the reactivity of the reductants and to the structure of the complexes is made.
- Research Organization:
- Nuclear Research Centre-Negev, Beersheba, Israel
- OSTI ID:
- 5335575
- Journal Information:
- Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 72:1; ISSN RAREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
560111 -- Radiation Effects on Biochemicals-- In Vitro-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINO ACIDS
AZOLES
CARBOXYLIC ACIDS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
COPPER COMPOUNDS
DECOMPOSITION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
IMIDAZOLES
IRRADIATION
LEPTONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PEPTIDES
PH VALUE
PROTEINS
PULSED IRRADIATION
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
REDUCTION
TRANSITION ELEMENT COMPOUNDS