Professor Weinberg says that once enzymes are denatured by heat for example, the are unable to reform their native 3D shape. Assuming that heating doesn't change the primary structure, are the amino acids chemically altered during heating since they are unable to reform the chemical interactions that gave the protein its native shape prior to heating?

Question

Professor Weinberg says that once enzymes are denatured by heat for example, the are unable to reform their native 3D shape.  Assuming that heating doesn't change the primary structure, are the amino acids chemically altered during heating since they are unable to reform the chemical interactions that gave the protein its native shape prior to heating?

blues · Answer

Denaturing any protein by whatever means definitely does not change the primary structure. Nor do denaturing conditions alter the chemical configurations of side chains, once the initial conditions have been restored.

Some proteins which have been experimentally denatured can spontaneously refold and regain function, especially small ones. Others can't refold unless without the assistance of specialized 'assistant' proteins called chaperones. Usually these proteins will partially refold but will become stuck in partially folded but energetically favourable conformations, or will refold but into some other incorrect configuration. 

When this happens, the side chains are still able to form all their initial and appropriate chemical bonds. They just happen to form other bonds with different, inappropriate side chains or with entirely different molecules in the vicinity at the time.

anonymous · Answer

Thank you for answering my question. I didn't realize than some proteins need help to get into their proper shape. I though is was strictly based on chemical interaction.