Re: Is there any different between denaturation and precipitation of protein?

Denaturation and precipitation are in fact different things, even though they are often linked in protein chemistry. Denaturation is the loss of native conformation of a protein's structure. Most proteins contain a mix of hydrophilic and hydrophobic amino acids and their normal conformations hide the hydrophobic residues in the proteins' cores. When these proteins are unfolded (denatured) the hydrophobic residues are no longer hidden and the protein becomes less soluble, which leads to its precipitation out of aqueous solution. So in most cases, denaturation of proteins causes their precipitation. One way to avoid this, is to denature the proteins in the presence of detergents: in the lab we use sodium lauryl sulfate (also found in many household detergents) to denature proteins before running them out on separating gels because it completely denatures them while also preventing their precipitation. Other denaturants, like guanidium or urea are often used to denature proteins without precipitating them, especially if the proteins need to be "renatured" later on.