STRUCTURE OF THE N-TERMINUS OF THE ESCHERICHIA-COLI RIBOSOMAL-PROTEINL7 L12/

Three mutant forms of the ribosomal protein L7/L12 (S1Y, M14Y and M26Y ) were constructed in order to use the Tyr residues as internal labels at the N-terminal region. The proteins were studied by the methods of H-1-NMR, Fluorescence, Circular dichroism spectroscopy and Differenci al scanning calorimetry. The secondary structure of N-terminus (residu es 1-36) was predicted by the programme ''Globule'' [1, 2]. Y1 is loca ted in a structurally disordered region at the free end of the molecul e. M14 and M26 are located in structurally ordered regions. The replac ement M14 does not change the structure of the protein. The replacemen t M26 disturbs the helicity in the region of the mutation. The first 1 -5 positions from the N-terminus of L7/L12 are disordered, the positio ns 7-14 participate in an alpha-helical/ beta-structural region and po sitions 19-30 in a strongly alpha-helical region.