Double‐Stranded Polydeoxyribonucleotides Containing 6‐Thiodeoxyguanosine and 6‐Thiodeoxyinosine
Poly[d(A‐C) · d(T‐s6G)], Poly[d(A‐s6G) · d(T‐C)] and Poly[d(A‐C) · d(T‐s6I)]
Definition. A260 unit, the quantity of material contained in 1 ml of a solution which has an absorbance of 1 at 260 nm, when measured in a 1‐cm pathlength cell.
Abstract
Three new double‐stranded polydeoxyribonucleotides containing the nucleoside analogs 6‐thiodeoxyguanosine and 6‐thiodeoxyinosine were synthesized enzymatically. Poly[d(A‐C) · d(T‐s6G)] and poly[d(A‐s6G) · d(T‐C)] were prepared by extensive synthesis with DNA polymerase from Micrococcus luteus, while the same enzyme from Escherichia coli failed in extensive polymerisation but brought about the synthesis of poly[d(T‐s6G)] and poly[d(T‐s6I)] by the repair mechanism using single‐stranded poly[d(A‐C)] template and a minute amount of d(T‐G)n primer.
The analog‐containing DNAs were characterized by ultraviolet absorption and circular dichroism spectra as well as by their stability against thermal and alkaline denaturation. The substitution by 6‐thiodeoxyguanosine or 6‐thiodeoxyinosine for deoxyguanosine reduces the stability of the biopolymers considerably. Exchange of the analog‐containing strand by singlestranded poly[d(T‐G)] takes place rapidly even at ambient temperature.
Number of times cited: 6
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