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Protein denaturant guanidine hydrochloride (50-01-1) and urea, which one is better?

2017-02-09 来源:亚科官网
9 February 2017
  Proteins are responsible for complex biochemical reactions, in the exercise of biological function, it must have a specific three-dimensional spatial structure. After biosynthesis, the protein itself undergoes a complex physiological process. In biochemical tests, researchers often need to study the denaturation and renaturation of protein, guanidine hydrochloride and urea are the most commonly used reagents, then what is the difference between the two reagents?
  Due to external factors, conformational abnormal changes happen in the natural protein molecules, resulting in the loss of biological activity and abnormal changes of physical and chemical properties, this phenomenon is known as the protein denaturation. Denaturation can involve the cleavage of secondary bonds, disulfide bonds, but not the cleavage of peptide bonds on the primary structure.
  Guanidine hydrochloride and urea denatured protein include two mechanisms: the first mechanism is that denatured protein and guanidine hydrochloride and urea preferentially combine to form complexes, when the complex is removed, the reaction equilibrium moves. With the increasing of denaturant concentration, the natural state of the protein changes into a complex, resulting in complete denaturation of proteins; the second mechanism is the guanidine hydrochloride and urea has solubilization of hydrophobic amino acid residues. because the guanidine hydrochloride and urea have the ability to form hydrogen bonds, in the high concentration (4~8mol/L) aqueous solution, they can break hydrogen bonds, then become a better solvent for non-polar residues, so that protein molecules within the hydrophobic residues stretch and solubility increased, protein degeneration occurs to varying degrees.
  The differences between guanidine hydrochloride and urea:
  Concentration: At room temperature, 3~4mol/L guanidine hydrochloride can make the globular protein to the midpoint from the natural state to the denaturation state, usually increased denaturant concentration can improve the degree of denaturation, about 6mol/L guanidine hydrochloride can make the protein completely into degeneration state. The guanidine hydrochloride has an ionic property and is superior to urea in denaturation. Some globular proteins can not be completely denatured even in 8mol/L urea solution. However, in 8mol/L guanidine hydrochloride solution, they exist in random conformation (complete denaturation).
  Solubility: Urea dissolves slowly and weakly than guanidine hydrochloride. Its solubility is 70%~90%. Urea can be decomposed to form cyanate when the action time is longer or the temperature is higher, and the amino group of the recombinant protein is covalently modified. It has the advantages of non-ionization, neutrality and low cost. The solubility of guanidine hydrochloride is more than 95%, and the dissolution is fast without causing the covalent modification of recombinant protein, but the cost is higher than that of urea, it is easy to produce precipitation under acidic condition, and it have interference on the follow-up experiments.
  In general, as commonly used reagents in protein denaturation process, guanidine hydrochloride and urea have the following advantages and disadvantages: the guanidine hydrochloride dissolves and denatures relatively strong and does not cause the covalent modification of the recombinant protein, but the cost is higher, it is easy to produce precipitation in acidic conditions, has interference on ion exchange chromatography; the solubility of urea is relatively weak, but non-ionizing, neutral, low cost, and it will not cause a lot of protein precipitation after protein refolding. In practical experiments, the researchers need to select according to the conditions and objectives in order to obtain the best experimental results.
Edited by the Editorial Office of Suzhou Yacoo Science Co., Ltd.