Q.What is denaturation of a protein? Name three agents or conditions that can cause it.

Denaturation is the loss of a protein's natural, biologically active three-dimensional shape -- and, along with it, the loss of its normal biological activity -- caused by physical or chemical agents that disrupt the folded structure of the polypeptide chain, without breaking the peptide bonds of its primary structure.

Common causes include: heat, which increases molecular motion enough to disrupt the interactions holding the folded shape together; extremes of pH (strongly acidic or strongly alkaline conditions), which alter the ionisation state of acidic and basic side chains and disturb the pattern of attraction stabilising the fold; and heavy-metal ions, such as $\text{Hg}^{2+}$ or $\text{Pb}^{2+}$, which can bind to specific groups on the pr …

List the disruptive agents that affect a protein's weak, non-covalent folding interactions -- heat, pH extremes, …

Assuming denaturation requires breaking covalent peptide bonds -- it does not; it disrupts only the weaker, non-covalent interactions resp …