One thus obtains a profile relating the global protein signal to the denaturant value. It can also be used as a protein denaturant. When the fragment reaches its melting point (threshold of enough denaturant), it stops moving. For nucleic acids, urea is the most commonly used denaturant. A denaturant such as gasoline is added to render the product undrinkable. Similar to circular dichroism, the stimulus for folding can be a denaturant or temperature. Folding intermediates for this protein can be studied using light spectroscopy and denaturant. The denaturant can be a chemical molecule (urea, guanidinium hydrochloride), temperature, pH, pressure, etc.