Charge transfer in peptides. Pulse radiolysis investigation of one-electron reactions in dipeptides of tryptophan and tyrosine.
Prütz, W Land, Edward J
Prütz, W
Land, Edward J
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Abstract
One-electron oxidation of TyrOH-TrpH or TrpH-TyrOH in aqueous solutions by N3 radicals occurs predominantly at the tryptophyl residue. The corresponding indolyl radicals (absorbing at 510 nm) are subsequently transformed into phenoxyl radicals (absorbing at 390/405 nm): TyrOH-Trp leads to TyrO-TrpH, k5 = 5.4 x 10(4)s-1, (5), Trp-TyrOH leads to TrpH-TyrO, k7 = 7.3 x 10(4)s-1. (7) The first-order radical transformation rates are independent of the (initial) concentration of N3 or peptide and unaffected by urea (as a modifier of hydrogen bond structures). Intermolecular conversion of indolyl into phenoxyl radicals, e.g. by reaction of GlyH-Trp with TyrOH-GlyH, is very slow and inefficient. It is concluded that reactions (5) and (7) occur by intramolecular charge transfer across the peptide bond.
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1979-11
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Charge transfer in peptides. Pulse radiolysis investigation of one-electron reactions in dipeptides of tryptophan and tyrosine. 1979, 36 (5):513-20 Int J Radiat Biol Relat Stud Phys Chem Med