43] Ribosomal synthesis of polypeptides from aminoacyl-tRNA without polynucleotide template

Abstract

Publisher Summary This chapter describes the ribosomal synthesis of polypeptides from aminoacyl-tRNA without polynucleotide template. The best substrate for the ribosomal template-free peptide synthesis was lysyl-tRNA. It has been shown that it is the structure of the tRNA and not the nature of the amino acid residue that determines the ability of the aminoacyl-tRNA to participate in peptide elongation on ribosomes. The chapter also presents other aminoacyl-tRNA that were studied as substrates for the ribosomal peptide synthesis in the absence of the template include seryl tRNA, threonyl-tRNA, and aspartyl-tRNA. Template-free synthesis of polypeptides was strongly dependent on the two elongation factors (EF-Tu and EF-G) and GTP. A summary of the results of the experiments is mentioned in this chapter and those with 13 other aminoacyl-tRNA in the same binding and polymerization systems under optimal Mg 2+ concentration is also presented in the chapter. A comparison of optimal Mg 2+ concentrations for polymerization of aminoacyl residues on ribosomes without template polynucleotides has shown that they lie in the range from l0 to 15 mM MgCl 2 .