Proteins interact with DNA through electrostatic interactions (salt bridges), dipolar interactions (hydrogen bonding, H-bonds), entropic effects (hydrophobic interactions) and dispersion forces (base stacking). These forces contribute in varying degrees to proteins binding in a sequence-specific or non–sequence-specific manner.
Limitations. detect low abundance DNA binding proteins from lysates. test binding site mutations using many probe configurations with the same lysate. test binding affinity through DNA probe mutational analysis. non-radioactive EMSA possible using biotinylated or fluorescently labeled DNA probes.
Gas exchange occurs at the alveoli in the lungs and takes place by diffusion. The alveoli are surrounded by capillaries so oxygen and carbon dioxide diffuse between the air in the alveoli and the blood in the capillaries
