Osmotic Effectors and DNA Structure: Effect of Glycine on Precipitation of DNA by Multivalent Cations

Abstract

We have investigated the effect of glycine (an organic osmolyte) on DNA precipitation induced by spermine⁴⁺, spermidine³⁺ and Tb³⁺ addition, using circular dichroism (CD), UV spectroscopy (UV), and electric linear dichroism (ELD) techniques.

DNA precipitation by the three compounds is perturbed by glycine: more spermine⁴⁺, spermidine³⁺ and Tb³⁺ must be added to obtain the same extent of precipitation as compared to the behaviour in absence of this organic osmolyte. It seems that glycine has a general effect on the DNA environment. Calculations based on experimental results and Manning's coun- terion condensation theory show that glycine could modify the electrostatic environment of DNA as a consequence of a change in dielectric constant.