Methionyl----tyrosyl radical transitions initiated by Br2-. in peptide model systems and ribonuclease A.
Prütz, W A Butler, John Land, Edward J
Prütz, W A
Butler, John
Land, Edward J
Citations
Altmetric:
Abstract
A series of radical transitions, Br2-.----Met(S therefore Br)----Trp(indolyl)----Tyr (phenoxyl), has been demonstrated by pulse radiolysis of N2O-saturated aqueous solutions containing Br-, Met-Gly and Trp-(Gly)2-Tyr at pH 6.7. The intramolecular Met(S therefore Br)----Trp(indolyl) transition in the dipeptide Met-Trp is shown to proceed via the Trp+. radical cation, with a rate constant of k approximately 10(7)s-1, consistent with an electron transfer. Br2-.-attack upon ribonuclease A (RNase) leads to a fast Met(S therefore Br)----Tyr(phenoxyl) process, k = (4.0 +/- 1.0) X 10(5)s-1, probably involving the solvent-exposed Met-29 and the adjacent Tyr-25. Phenoxyl dimerization in the RNase system produces the characteristic o,o'-biphenol fluorescence, but a competing interaction of the Tyr-25(phenoxyl) with the 26-84 disulphide group also appears possible.
Authors
Description
Date
1985-02
Publisher
Collections
Keywords
Type
Article
Citation
Methionyl----tyrosyl radical transitions initiated by Br2-. in peptide model systems and ribonuclease A. 1985, 47 (2):149-56 Int J Radiat Biol Relat Stud Phys Chem Med