Polynucleotides

XXI. Synthesis and Properties of Poly 1-Deazaadenylic Acid and Poly 3-Deazaadenylic Acid

Abstract

Poly 1-deazaadenylic acid (poly 1-deazaA) and poly 3-deazaadenylic acid (poly 3-deazaA) were synthesized from 1-deaza and 3-deaza ADP by the use of E. coli polynucleotide phosphorylase [EC 2. 7. 7. 8]. In the latter case, incubation was carried out at 60°C and in the presence of Mn²⁺.
In neutral solution, poly 1-deazaA and poly 3-deazaA had hypochromicities of 42 and 32%, respectively. From the CD spectra and Tm profiles, a stacked conformation for both polynucleotides was assigned. Under acidic conditions poly 1-deazaA formed a protonated double-stranded complex, with Tm at 40°C. The acid form of poly 3-deazaA showed a Tm of over 80°C.
The mode of hydrogen bonding in the complex (poly 1-deaza A)•(Poly U) is suggested to be Hoogsteen type or reverse Hoogsteen type instead of the usual Watson-Crick type. By contrast, poly 3-deazaA formed both 1:1 and 1:2 complexes with poly (U) having Tm's of over 80°C.