Electron spin resonance study of liquids during photolysis. 21. Dipeptides

Autor:	David G. Doherty, Henry Zeldes, Ralph Livingston
Rok vydání:	1976
Předmět:	Hydrogen Radical chemistry.chemical_element General Chemistry Photochemistry Hydrogen atom abstraction Biochemistry Peroxide Catalysis law.invention chemistry.chemical_compound Colloid and Surface Chemistry chemistry law Side chain Electron paramagnetic resonance Isopropyl Methyl group
Zdroj:	Journal of the American Chemical Society. 98:7717-7723
ISSN:	1520-5126 0002-7863
DOI:	10.1021/ja00440a044
Popis:	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.
Databáze:	OpenAIRE
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