... FEBSbean and soybean. When binding of arginine in the presence of tRNA was investigated, some changes in the binding architecture were observed [35], in thatN(153:Y), in addition to interacting with ... N of the guanidine group that isreplaced by the heteroatom in l-thioarginine, locking the guanidino nitrogens into the arginine-like tauto-meric form. As we have shown that l-thioarginine is ... tRNA binding is notrequired for arginine binding [33], although arginine binding is a prerequisite for correct positioning of the CCA end, mediated through movement of a conservedtyrosine [Y(347:Y)]...