John J. Windle

An E.P.R. study of peptides after U.V. irradiation.

Abstract— Various peptides of Gly, Ala, Phe, Tyr, and Trp have been irradiated with U.V. light in the solid state or in frozen aqueous solution. The radicals produced were studied by E.P.R. spectroscopy at low temperature and at room temperature. Radicals seem to occur preferentially on Gly or Ala when in the C‐terminal position and there is evidence for a photosensitization of these amino acids by aromatic amino acids.

ELECTRON PARAMAGNETIC RESONANCE STUDY OF X-RAY AND

The following dipeptides have been irradiated with60 Co γ-rays in liquid nitrogen: glycyl-L-phenylalanine, glycyl-L-tyrosine, glycyl-L-tryptophane, L-phenylalanyl-glycine, L-tyrosyl-glycine, L-tryptophyl-glycine, L-alanyl-L-phenylalanine, L-alanyl-L-tyrosine, L-analyl-L-tryptophane, L-phenylalanyl-L-alanine, L-tyrosyl-L-alanine, and L-tryptophyl L-alanine. Their EPR spectra have been recorded at - 180 or - 160°C and at room temperature. Detectable free radicals are formed at low temperature only on glycine and alanine and are of the types -

gamma

\dot{{\rm C}}{\rm H}_{2}

-RAY IRRADIATED PEPTIDES IN THE SOLID STATE.

and -

Oxidation of N-methyl-γ-tocopheramine to a nitroxide

\dot{{\rm C}}{\rm H}\ ({\rm CH}_{3})

Two homogeneous immunoassays for pyridoxamine

respectively. Upon warming to room temperature the EPR signals of peptides containing glycine or alanine in the N-terminal position change to mostly unresolved spectra. For the C-terminal peptides, L-Phe-Gly and L-Tyr-Gly, warming results in a spectrum attributed to a

A Spin Probe Study of Cross-Linked Dextran Gels in Aqueous Media as a Model for Cell Walls

-{\rm NH}-\dot{{\rm C}}{\rm H}-{\rm COO}^{-}

Applications of electron paramagnetic resonance spectroscopy to the study of bio-membranes

radical, while for L-Phe-L-Ala, L-Tyr-L-Ala and L-Trp-L-Ala a spectrum believed to re...

ESR STUDY OF A NEW LIGHT-SENSITIVE FREE RADICAL IN THE COATS OF WHEAT AND OTHER SEEDS

An unstable nitroxide identified by electron paramagnetic resonance spectra was obtained by oxidation of N-methyl-γ-tocopheramine with peroxide and also by ultraviolet photooxidation.

Plasma synthesis of fluorocarbon films

Protein conjugates of pyridoxal have been used to elicit anti-vitamin B6 antibodies in rabbits. These antibodies have been incorporated into 2 homogeneous assays systems, a spin immunoassay, using a paramagnetic derivative of the vitamin as ligand, and a fluorescence enzyme immunoassay, using beta-galactosidase conjugated to vitamin B6 as the indicator molecule. These assay systems do not require fractionation steps, and could be the basis of analytical methodology for nutritional research or clinical diagnosis.