| Popis: |
Infrared spectra of E. coli ribosomes, and of extracted RNA and ribosomal proteins have been determined. From the spectra of stacked, single-stranded homopolyribonucleotides it is shown that the spectrum of a polynucleotide chain is essentially a function of the extent of base-pairing, and is only to a small extent affected by stacking. It is shown that the spectrum of the intact ribosome is the linear sum of contributions from native RNA (about 60% base-paired) and protein. It can not be expressed in terms of unpaired RNA. It is thus clear that the conformation of the RNA in the ribosome is, at least in terms of the extent of base-pairing, very similar to that of free RNA in solution. The spectra of the whole ribosomal proteins have been examined in acid and in neutral solution; for the latter the procedure of Traub and Nomura was followed, as for preparation of the proteins for recombination with RNA to produce native subunits. In this state the infrared spectrum shows the proteins to be predominantly in the β-conformation. It is suggested that the concept of a native structure for the ribosomal proteins is meaningful only in their native environment on the RNA. Parallels with histones and nucleohistones are noted. |
