L'vov K M, Ovcharenko V P, L'vova O F
Biofizika. 1978 Nov-Dec;23(6):970-3.
It has been shown that the limiting number of ionization acts (z) in a protein molecule in water solution UV-irradiated at 77 K is in proportion to the molecular weight: z=8.10(-6) M. Only one ionization is possible in simple protein with M=12,5.10(4). Radicals formed after one ionization protect from the effects of UV-radiation 60--150 adjacent residues of aromatic amino acids depending on their density in protein. Presence of the acceptors of excitation energy of aromatics residues (heme, eosin) results in a sharp decrease of limiting concentration of radicals in protein.
