[Supernarrow EPR spectrum of aqueous protein solutions, UV-irradiated at 77 K]

The nature was studied of paramagnetic centres photoinduced in aqueous solutions of proteins, amino acids and peptides at 77 K, having a supernarrow ESR spectrum with the width 8 mkTl and g = 1.9988 +/- 0.0002. It has been shown that seized electrons localized in deep traps are responsible for this signal. It is suggested that these are metal ions whose nucleus magnetic moment equals zero.