Opposite effect of polyamines on <i>In vitro</i> gene expression: Enhancement at low concentrations but inhibition at high concentrations - Fig 1

Chemical formulas of (A) spermidine, [SPD(3+)] and (B) spermine, [SP(4+)].</p

Gene expression efficiency depending on the DNA concentration at a fixed concentration of SPD(3+), 1.5 mM.

<p>Gene expression efficiency depending on the DNA concentration at a fixed concentration of SPD(3+), 1.5 mM.</p

AFM images of DNA conformations at different concentrations of SP(4+).

<p>SP(4+) concentration is (A) 0.004 mM (control), (B) 0.007 mM, (C) 0.06 mM, and (D) 0.6 mM.</p

AFM images of DNA conformations at different concentrations of SPD(3+).

SPD(3+) concentration is (A) 0.004 mM (control), (B) 0.1 mM, (C) 0.3 mM, and (D) 2 mM.</p

Gene expression efficiency depending on the concentrations of polyamines, SPD(3+) and SP(4+).

The longitudinal axis shows the relative emission intensity of luciferin-luciferase reaction, which corresponds to the efficiency of gene expression. DNA concentration was fixed at 0.3 μM.</p

Schematic representation of the nature of the interaction of polyamine with DNA and also with RNA polymerase depending on the polyamine concentration.

(A): elongated DNA without polyamine, (B): parallel alignment of DNA segments with the inset of the AFM image of Fig 5(C), (C): compact DNA with the inset of AFM of Fig 5(D).</p