title: Synthesis of compositionally unique DNA by terminal deoxynucleotidyl transferase.
abstract: Studies on the composition and characterization of DNA product(s) synthesized by calf thymus terminal deoxynucleotidyl transferase were performed using homopolymeric single-stranded, calf thymus double-stranded, and native DNA resident in calf thymus chromatin preparations as priming DNA species. Synthesis was carried out using equimolar concentrations of all four deoxynucleoside triphosphates as substrates and Mg2+ or Mn2+ as an effective divalent cation. Irrespective of the nature of the priming DNA or the divalent cation, the DNA product contained 60-70% dGMP residues, 10-15% each of the two pyrimidine residues, and 5-10% dAMP residues. The product synthesized using chromatin DNA as initiator was predominantly single-stranded and its synthesis was resistant to actinomycin D. The predilection of terminal deoxynucleotidyl transferase to synthesize dGMP-rich products on natural or homopolymeric DNA primers suggests that such products may represent biologically important recognition signal sequences.
mesh_terms: D000818:Animals; D002384:Catalysis; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis*; D004253:DNA Nucleotidylexotransferase / Q000378:metabolism*; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D006157:Guanosine Monophosphate / Q000302:isolation & purification; D013950:Thymus Gland / Q000201:enzymology
chemical_list: D002843:Chromatin; D006157:Guanosine Monophosphate; D004247:DNA; D004254:DNA Nucleotidyltransferases; D004253:DNA Nucleotidylexotransferase