denaturation

In biology, changes occurring in the structure of proteins such as enzymes, usually caused by changes in pH or temperature, by radiation, or by chemical treatments. An example is the heating of egg albumen resulting in solid egg white.

The enzymes associated with digestion and metabolism become inactive under abnormal conditions. Heat will damage their complex structure so that the usual interactions between enzyme and substrate can no longer occur.

In many cases, denatured proteins can be restored to their native structure in laboratory experiments. Typically, they are dissolved in a solution containing high concentrations of chemicals like urea to avoid aggregation, and then diluted rapidly into a suitable buffer. With such an experiment, known as renaturation or refolding, Christian Anfinsen demonstrated that the three-dimensional structure of a protein is determined exclusively by its amino acid sequence.