Oxidation of tryptophan and N-methylindole by N sub 3 sup sm bullet , Br sub 2 sup sm bullet minus , and (SCN) sub 2 sup sm bullet minus radicals in light- and heavy-water solutions: A pulse radiolysis study. [Accelerated electrons]

Journal Article · Thu May 02 04:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100162a038· OSTI ID:5952494

Solar, S; Getoff, N ^[1]; Surdhar, P S; Armstrong, D A ^[2]; Singh, A ^[3]

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1. Univ. of Vienna (Austria)
2. Univ. of Calgary, Alberta (Canada)
3. AECL Research, Pinawa, Manitoba (Canada)

Reactions of N{sub 3}{sup {sm bullet}}, Br{sub 2}{sup {sm bullet}{minus}}, and (SCN){sub 2}{sup {sm bullet}{minus}} with tryptophan (TRPH) and N-methylindole (NMI) have been investigated in H{sub 2}O and D{sub 2}O solutions. The main transients produced were the TRP{sup {sm bullet}} radical and the TRPH{sup {sm bullet}+} radical cation from TRPH and the NMI{sup {sm bullet}+} radical cation from NMI. Their extinction coefficients ({epsilon}) as well as the rate constants for their formation and decay were determined in the pH range 3-10. The pK of the TRPH{sup {sm bullet}+} radical cation was confirmed to be 4.2 {plus minus} 0.1. These rate constants were within experimental error, independent of pH, and the differences between the rate constants in H{sub 2}O and D{sub 2}O were small. On the basis of the results, it was concluded that of the two possible reactions - electron or hydrogen atom transfer - the data are more consistent with electron transfer in all cases. However, secondary acid-base reactions have an important effect on the overall redox equilibria, especially with N{sub 3}{sup {sm bullet}}. Experimental data on these effects have also been obtained.

• OSTI ID: 5952494
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:9; ISSN JPCHA; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ABSORPTION SPECTROSCOPY
AMINO ACIDS
ANTITHYROID DRUGS
AROMATICS
AZAARENES
AZIDES
AZOLES
BROMINE
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACIDS
CATIONS
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
DRUGS
ELECTRON TRANSFER
ELEMENTS
EXPERIMENTAL DATA
HALOGENS
HEAVY WATER
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HORMONE ANTAGONISTS
HYDROGEN COMPOUNDS
HYDROGEN TRANSFER
INDOLES
INFORMATION
IONS
KINETICS
MATHEMATICAL MODELS
NITROGEN COMPOUNDS
NONMETALS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
PH VALUE
PYRROLES
RADIATION EFFECTS
RADICALS
RADIOLYSIS
REACTION KINETICS
RESOLUTION
SPECTRA
SPECTROSCOPY
THIOCYANATES
TIME DEPENDENCE
TIME RESOLUTION
TIMING PROPERTIES
TRYPTOPHAN
VISIBLE SPECTRA
WATER