it was found that the esr spectra of ef-g labeled with nitroxide maleimide reagents were modified by the addition of various guanine nucleotides such as gdp , gtp and , to a lesser extent , by gpp ( nh ) p and gpp ( ch2 ) p , indicating that conformational changes accompany the binding of nucleotide ligand .
C0018328
guanine nucleotides
C0018353
gtp