A proteins life cycle begins once its gene is turned on and its mRNA is transcribed and translated to produce the polypeptide strand. The correct folding of a protein is the first crucial stage of the life cycle of a protein. Correct folding is essential for a protein to be functional, whereas incorrect folding can have severe detrimental effects. For example, several misfolded protein diseases include bovine spongiform encephalopathy (BSE) and its human equivalent Creutzfeld-Jakob disease (CJD), Alzheimer’s disease, Parkinson’s disease, type II (non-insulin dependent) diabetes and some types of cancer. The symptoms of Mad Cow Diseases (BSE) and Alzheimer’s are a result of misfolded proteins aggregating and forming insoluble protein deposits in the brain.
Protein unfolding and folding, a reversible process, is analyzed using a light emitting protein specifically prepared for this study and a protein electrophoresis technique. The kit allows students to see when a light emitting protein is denatured (unfolded) as it loses its property to emit light. After electrophoresis, the protein in the gel is subjected to a renaturation and folding treatment, which returns the protein to its natural configuration resulting in a return of the light emitting properties.
This lab activity teaches the following:
- The principles of protein denaturation and refolding.
- The importance of correct folding for protein activity.