[Accumulation of paramagnetic centers in protein solutions exposed to UV-radiation]

It is shown that concentration of paramagnetic centres (PC) in UV-irradiated protein solutions at 77degreesK approximates the limiting value. The limiting number of PC (n) per one molecule is in direct proportion to that of aromatic amino acid residues in it n(sigma)=2+0,1 sigma. The formation of PC slopps because all the energy absorbed by aromatic amino acid residues is transfered to the radicals formed.