Photolysis (193 nm) of Aliphatic Dipeptides in Aqueous Solution

Nikogosyan, David N.
Görner, Helmut

Max-Planck-Institut für Strahlenchemie, D-45413 Mülheim an der Ruhr, Germany
^aOn leave from the Department of Physics, University College Cork, Cork, Ireland

^*Corresponding author

Received March 17,1997; accepted May 26, 1997

Biological Chemistry 378(11):p 1349-1351, November 1997.

The photodecomposition of four aliphatic dipeptides containing valine and methionine was studied in neutral solution upon excitation at 193nm. The quantum yields of ionization and decomposition in Ar-saturated aqueous solution are Φ_e- = 0.06-0.16 and Φ_d = 0.06-0.16, respectively. Φ_d is enhanced (0.08-0.28) under N₂O, where the hydrated electrons are converted into OH radicals. A comparison of the Φ_d values of dipeptides with those of monomeric amino acids indicates efficient decomposition of the peptide bond (bond scission).