Hashimoto S, Kira A, Imamura M, Masuda T
Int J Radiat Biol Relat Stud Phys Chem Med. 1982 Mar;41(3):303-14. doi: 10.1080/09553008214551761.
Lysozyme dimers produced on oxidation of lysozyme with Br2 radical in aqueous solutions exhibit a fluorescence spectrum (lambda max = 400 nm) closely similar to that of bi-tyrosine. This suggests that the dimer is likely to have a tyrosine-tyrosine bond resulting from the combination of tyrosine phenoxy radicals of two lysozyme molecules. Kinetic studies on dimer formation were made by measuring time-dependent fluorescence after pulsed-electron irradiation over wide pH range. The results lead to the following conclusions. The second-order growth of the dimer fluorescence observed at pH 10.7-12.5 reflects the combination process of the lysozyme radicals, which is rate-determining in the pH range. On the other hand, the first-order growth observed at pH 6.8-10.2 is attributable to the enolization of the keto-form of the dimer. A tentative reaction scheme is proposed for the dimer formation.
