title: Poly(2-methylthio-7-deazainosinic acid)--hydrophobic stabilization of polynucleotide secondary structure by the 2-methylthio group.
abstract: Poly(2-methylthio-7-deazainosinic acid) [poly(ms2c7I)] was enzymatically synthesized by polymerization of 2-methylthio-7-deazainosine 5'-diphosphate with polynucleotide phosphorylase from Micrococcus luteus in high yield. The homopolymer shows much higher thermal stability than its parent polynucleotides poly(7-deazainosinic acid) [poly(c7I)] and poly(I). Its sigmoidal melting curve and pronounced hypochromicity imply a rigid, ordered structure. Poly(ms2c7I), like poly(2-methylthio-inosinic acid) [poly(ms2I)], does not form a complex with poly(C) because of the bulky 2-methylthio substituent. On the other hand, two poly(ms2c7I) strands form very rigid triple strands with poly(A). Different from poly(I) and poly(c7I) the homopolymer poly(ms2c7I) is very stable against cleavage by nuclease S1 and ribonuclease T2 as expected from its rigid secondary structure.
mesh_terms: D002942:Circular Dichroism; D004355:Drug Stability; D007202:Indicators and Reagents; D008745:Methylation; D008837:Micrococcus / Q000201:enzymology; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D011069:Poly I / Q000138:chemical synthesis*; D011117:Polyribonucleotide Nucleotidyltransferase; D011131:Polyribonucleotides / Q000138:chemical synthesis*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007202:Indicators and Reagents; D011131:Polyribonucleotides; D011069:Poly I; C039227:poly(2-methylthio-7-deazainosinic acid); D011117:Polyribonucleotide Nucleotidyltransferase