Denaturation is the alteration of a protein or nucleic acid's shape through any form of external stress (for example, by applying heat, acid or alkali), in such a way that it will not  be able to carry out its cellular function.

Irreversible egg protein denaturation and loss of solubility, caused by the high temperature (while cooking it)

Proteins are very long strands of amino acids linked together in specific sequences. A protein is created by ribosomes that "read" codons in the gene and put together the appropriate amino acid combination from the genetic instruction, also known as translation. The new protein strand then undergoes “posttranslational modification”, where additional atoms or molecules such as copper, zinc or iron  are added. Once post-translational modification  has been completed, the protein begins to fold (spontaneously, and sometimes with the help of enzymes), curling up on itself so that hydrophobic elements of the protein are buried deep inside the structure and hydrophilic elements end up on the outside. The final shape of a protein determines how it interacts with its environment.

When a protein is denatured, the secondary and tertiary structures are altered but the peptide bonds between the amino acids are left intact. Because the protien structure determines its function, the protein will no longer be able to perform its function once it has been denatured.
Denaturing  of DERp1 and DERp2 occurs as follows

Quaternary structure denaturation: protein sub-units are dissociated and/or the spatial arrangement of protein subunits is disrupted”.

Tertiary structure denatuation: disruption of

• Covalent bonds between amino acid chains
• Noncovalent dipole-dipole interactions between polar amino acid chains and surrounding solvent.
• Van Der Waal's interactions between nonpolar amino acid side chains.