DEMONSTRATION OF SEGMENTAL MOBILITY IN THE FUNCTIONALLY ESSENTIAL CARBOXYL-TERMINAL PART OF RIBONUCLEOTIDE REDUCTASE PROTEIN R2 FROM ESCHERICHIA-COLI

The C-terminus of protein R2 is important for the formation of the enz ymatically active complex between proteins R1 and R2 of ribonucleotide reductase from Escherichia coli. Some residues in this part of R2 may also be involved in intramolecular electron transfer. We now demonstr ate that 26 amino acid residues at C-terminus of protein R2 are mobile in the free protein, and can be studied by H-1 NMR. Spectral assignme nt of narrow resonances was made by comparison of TOCSY and NOESY spec tra from wild-type R2 with corresponding spectra of a mutant protein R 2, lacking 30 residues at the carboxyl terminus.