Investigation of the structure and local conformational transitions of proteins and enzymes by the method of double paramagnetic labels

A method has been worked out for studying the relative position and molecular movements of protein groups based on the specific chemical modification of these groups by derivatives of iminoxyl stable radicals and by complexes with paramagnetic metals with subsequent study of the effects of the interaction by the EPR method. The method of double paramagnetic labels has established that in bovine haemoglobin at a distance of about 15 Å from the β = 93 SH group there is a histidine residue and that in human serum albumin it is possible to distinguish three types of lysine groups next to which are situated guanidine, histidine and tyrosine groups respectively.