The radiation protective effect of the breaking of secondary bonding in protein was examined with such amino acids as disodium inosine-5′ -monophosphate and disodium guanosine-5′ -monophosphate and vitamins such as thiamine and λ-ascorbic acid. The behavior of the viscosity change closely resembles that found with the sodium 1-glutamate as shown by a similar dependence on concentration.