title: Favored incorporation of tubercidin in poly(adenylic, 7-deazadenylic acids) and their function as messenger ribonucleic acids in protein synthesis.
abstract: The following polynucleotides containing the antibiotic tubercidin (Tu; 4-amino-7-beta-D-ribofuranosylpyrrolo-[2,3-d]pyrimidine) were enzymatically synthesized by polymerization of adenosine 5'-diphosphate-tubercidin 5'-diphosphate mixtures with polynucleotide phosphorylase: poly(A2,Tu), poly(A,Tu2), and poly(Tu). The incorporation of the antibiotic was favored by the enzyme. The polymers are compared to poly(adenylic acid) [poly(A)] with respect to their structure, conformation, and ability to direct polylysine synthesis in a ribosome-dependent protein synthesis system. From physical data (thermal melting, NMR, and circular dichroism) it is concluded that tubercidin destabilizes the structure of the polynucleotide chain and that this may be due to an altered polarization of the nucleobases and their enhanced rotation around the N-glycosylic bond. Since there is an apparent correlation between thermal unfolding of the polymers and their ability to mediate polylysine synthesis, it is suggested that partial destacking of the messenger ribonucleic acid favors its binding to the ribosome and/or its ability to enhance codon-anticodon-specific protein synthesis.
mesh_terms: D002942:Circular Dichroism; D007700:Kinetics; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D011061:Poly A / Q000096:biosynthesis*; D011107:Polylysine / Q000096:biosynthesis; D011117:Polyribonucleotide Nucleotidyltransferase / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics*; D012263:Ribonucleosides / Q000378:metabolism*; D012265:Ribonucleotides / Q000378:metabolism; D014372:Tubercidin / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D012263:Ribonucleosides; D012265:Ribonucleotides; D011061:Poly A; D011107:Polylysine; C008956:polydeazaadenylic acid; D011117:Polyribonucleotide Nucleotidyltransferase; D014372:Tubercidin