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Mechanism and Difference of Guanidine Hydrochloride and Urea as Denaturant 2018-03-30 10:04:41

Denaturation is the physical or chemical effect on proteins which result in its structure and property change. The change and deterioration of secondary and tertiary structures for the protein show its denaturation. Some reagents, such as guanidine hydrochloride and urea, will make protein denaturize. The reagents are known as denaturants. In the following, two denaturants guanidine hydrochloride and urea are discussed.


Firstly, the mechanism of protein denaturation of guanidine hydrochloride and urea were illustrated. There are three suggested mechanisms for the above denaturants. The first statement is the hydrogen bond broken which make the protein structure flexible. The second one is the denaturant which deteriorate the hydrophobic effect. The third one is that the denaturant make hydrophobic amino acid residues more soluble.


In the protein denaturation, the concentration and solubility of these two denaturants are different. In the room temperature, 3-4 mol/L guanidine hydrochloride solutions can make protein change from native state to the middle point of the denaturation. In general, high concentration will enhance the denaturation. About 6 mol/L guanidine hydrochloride will make protein denaturize completely. Due to the ionic nature of the guanidine hydrochloride, its denaturation ability is stronger than urea. For example, 8 mol/L urea solutions cannot make some globular protein denaturize completely, but it is not the case for guanidine hydrochloride which can result in the fully denaturized protein. In addition, solubility is poorer for urea than guanidine hydrochloride. Urea will decompose to cyanate and modify amino group of recombinant protein for longer reaction time or in the high temperature. But it has some advantages with nonionization, neutrality and low cost etc. Guanidine hydrochloride can solve rapidly and does not modify the recombinant protein. But the cost is higher than urea, easy to precipitate in acid condition which may interfere with subsequent experiments.


In a word, the two denaturants have their own advantages and disadvantages. Researchers must select an appropriate denaturant according to the designed experiment.


Edited by Suzhou Yacoo Science Co., Ltd.

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