Polyamine binding sites on Escherichia coli ribosomes.

To determine the binding sites of polyamines on Escherichia coli ribosomes, ribosomal proteins crosslinked with polyamines through bifunctional reagents were analyzed. When 1,5-difluoro-2,4-dinitrobenzene was used as a crosslinking reagent, spermine was bound to S3, S8, S9, L1, L2, L3, L5, L6, L13, L18, L24, and L27 proteins. When dimethyl suberimidate was used, spermine was bound to S1, S3, S4, S5, S7, S8, S9, S15, L1, L2, L3, L6, L18, and L24 proteins. In addition to crosslinking with the above proteins, spermidine, when crosslinked with dimethyl suberimidate, bound to S2, S14, S20, L4, L5, L9, L13, and L16 proteins. The relationship between the binding site(s) of polyamines on ribosomes and the function of polyamines is discussed.