1 – The Chemical Modification of Proteins by Group-Specific and Site-Specific Reagents

Publisher Summary This chapter reviews that the properties of ribosomes from escherichia coli have been widely studied. It focuses on two aspects—namely, structure and function. The structural aspects are considered concerning, the primary structure of the ribosomal proteins and ribosomal ribonucleic acid (RNA), the interaction between proteins and RNA, and the topographical arrangement of the proteins. The functional aspect is subdivided into considerations of initiation of protein synthesis, elongation and termination. The chapter discusses that the amino acid and nucleotide sequences of a substantial number of the ribosomal proteins and nucleic acids have now been established, and it can be expected that the primary structures of all the ribosomal components will soon be determined. On the other hand, the problem of how these components are arranged within the ribosomal particles remains one of the most challenging questions in ribosome research. A final solution to this topography problem is too complex even to contemplate at the present time, but the techniques that are summarized here for the investigation both of RNA–protein interactions and the spatial organization of the proteins, have already led to a crude understanding of many features of the ribosomal structure.

The ribosome of Escherichia coli.

Reactive properties of the amino groups of histones in calf thymus chromatin

An analysis of alterations in ribosomal conformation using reductive methylation.

Experimental procedures developed for the identification of near-neighboring proteins in a complicated organelle are described in this paper. The specific system studied here is the ribosome ofEscherichia coli; however, the techniques and reagents described should have a wide range of applications. We have used three kinds of cross-linking reagents: noncleavable maleimide reagents which react with free SH groups; noncleavable diimidoesters which react with free amino groups, and cleavable diazide reagents that also react with free amino groups. The combination of immunological and isotopic labelling techniques used to identify proteins cross-linked by noncleavable reagents, as well as the special electrophoretic techniques used with the cleavable reagents are described. We show that the neighborhoods detected by the crosslink technology are functionally meaningful ones, and also discuss the ambiguities inherent in the structural interpretation of such protein neighborhoods.

Chemical determination of protein neighbourhoods in a cellular organelle

Reactivities of ribosomal proteins toward acetic anhydride as determined by competitive labelling give numerical estimates of their exposure and deflect the interrelationships in the macrostructure.

M. Yaguchi

Papers

Structure of the ribosome: exposure of ribosomal proteins determined by competitive labeling.