Q.Does denaturation break the peptide bonds of a protein's primary structure? Explain how denaturation affects a protein's biological activity.

Denaturation affects only the weak, non-covalent interactions (such as hydrogen bonds and other attractions between side chains and backbone atoms) that hold a protein's higher-order folded shape together. It does not break the covalent peptide bonds that link the amino acids together in the primary structure -- the exact amino-acid sequence remains completely intact throughout denaturation.

What denaturation destroys instead is the protein's correctly folded, three-dimensional conformation. Since a protein's biological activity -- whether it is acting as an enzyme, a structural material, or anything else -- depends entirely on having that precise, correctly folded shape (for an enzyme, specifically the shape of its active site), losing that shape almost always means losing the biological …

Separate the two levels clearly: primary structure (peptide-bond sequence, unaffected) versus folded shape (secondary/tertiary structure, destroyed) -- th …

Assuming denaturation 'breaks the protein apart' at the amino-acid level -- it does not cleave any peptide bonds; the sequen …