How human serum albumin recognizes DNA and RNA

Abstract

AbstractWe show here for the first time that HSA possesses two nucleic acid-(NA) binding sites and we estimated the relative contributions of the nucleotide links of (pN)nto their total affinity for these binding sites with higher and lower affinity for NAs. The minimal ligands of these binding sites areorthophosphate (Kd=3.0 and 20.0 mm), various dNMPs (5.6–400 μmand 0.063–18 mm) and different rNMPs (4.9–30 μmand 14–250 μm). Maximal contribution to the total affinity of all NAs to the first and second sites was observed for one nucleotide and was remarkably lower for three additional nucleotide units of (pN)n(n=1–4) with a significant decrease in the contribution at n=5–6, and at n≥7–8 all dependencies reached plateaus. For d(pA)nand r(pA)na relatively gradual decrease in the contribution to the affinity at n=1–6 was observed, while several d(pN)n, demonstrated a sharp increase in the contribution at n=2–4. Finally, all (pN)n>10demonstrated high affinity for the first (1.4–150 nm) and the second (80–2400 nm) sites of HSA. Double-stranded NAs showed significantly lower affinity comparing with single-stranded ligands. The thermodynamic parameters characterizing the specific contribution of every nucleotide link of all (pN)1−9(ΔG°) to their total affinity for HSA were estimated.