INVESTIGATION OF THE CONFORMATIONAL PROPERTIES OF RIBOSOMES USING N-ETHYLMALEIMIDE AS A PROBE

The reactivity of ribosomal proteins towards N-ethylmaleimide was examined in a variety of ribosome and ribosomal subunit preparations from Escherichia coli. Samples which would be regarded as equivalent operationally can differ significantly in conformation, as judged by reactivity, depending on the preparation method. The washing of ribosomes with high concentrations of salt has a particularly dramatic effect on protein reactivity. The implications of these results in the understanding ribosome conformation and for the further study of conformation by chemical reactivity are discussed.