Electron spin resonance study of liquids during photolysis. XXI. Dipeptides

Journal Article · Wed Nov 24 04:00:00 EST 1976 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00440a044· OSTI ID:7332440

Doherty, D G; Livingston, R; Zeldes, H

Aqueous solutions of dipeptides containing about 1% hydrogen peroxide have been photolyzed at room temperature and the resulting radicals studied by electron spin resonance. The peroxide gives OH which abstracts hydrogen from the peptide. Radicals are formed from L-prolyglycine and ..beta..-alanyl-L-proline by abstraction of hydrogen from the carbon located between the peptide nitrogen and carboxylate group. In the latter case the spectrum is affected by the presence of cis-trans isomers and dynamic phenomena. In both ..beta..-alanyl-L-valine and glycyl-L-valine the abstraction is almost entirely from the isopropyl side chain giving a mixture of radicals corresponding to loss of one or the other kind of hydrogen in the isopropyl group. Hydrogen is abstracted from the methyl group of ..beta..-alanylsarcosine to give a mixture of cis and trans forms of the radical. Glycyl-L-aspartate and ..beta..-alanyl-L-aspartate each give a mixture of two radicals. One of these is a direct result of hydrogen abstraction from the side chain while the other involves chemical modification of the side chain. Hyperfine couplings and g values have been measured and are discussed.

• Research Organization: Oak Ridge National Lab., TN
• OSTI ID: 7332440
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 98:24; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400104 -- Spectral Procedures-- (-1987)
400500* -- Photochemistry
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COUPLING CONSTANTS
DECOMPOSITION
ELECTRON SPIN RESONANCE
G VALUE
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
HYDROXYL RADICALS
KINETICS
MAGNETIC RESONANCE
MEDIUM TEMPERATURE
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PEPTIDES
PEROXIDES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PROTEINS
RADICALS
REACTION KINETICS
RESONANCE
YIELDS