Proteins carry out complex biochemical reactions and must possess a special three-dimensional spatial structure when performing microbial functions. After microbial generation, proteins themselves also undergo complex physiological processes firsthand. In biochemical experiments, it is often necessary to conduct scientific research on protein denaturation. Guanidine hydrochloride and urea are the most commonly used experimental reagents in protein denaturation. So, what are the differences between the two? How to choose in the experiment?
Due to the efficacy of external factors, the conformation of pure natural protein molecules undergoes abnormal changes, resulting in the loss of biological activity and abnormal changes in their physical and chemical properties. This type of situation is called protein denaturation. Transduction can involve the rupture of secondary bonds and disulfide bonds, but not the rupture of peptide bonds on the primary structure.
Guanidine hydrochloride and urea transgender proteins contain two systems: the first system is the preferential fusion of transgender proteins with guanidine hydrochloride and urea, producing nitric oxide synthase. When nitric oxide synthase is removed, it reflects a shift in equilibrium, accompanied by an increase in the concentration of the denaturing agent. The protein in pure natural conditions continues to change into nitric oxide synthase, ultimately leading to complete protein transgender; The second system is the solubilization effect of guanidine hydrochloride and urea on hydrophobic amino acid residues. Due to the ability of guanidine hydrochloride and urea to form covalent bonds, the covalent bonds of guanidine hydrochloride and urea need to be broken in high concentration (4-8 mol/L) solutions. As a result, guanidine hydrochloride and urea become good organic solvents for non-polar residues, causing the hydrophobic residues inside the protein molecular structure to flex and increase solubility, leading to different levels of protein denaturation.
The difference between the two in protein conversion:
Concentration value: At indoor temperature, 3-2mol/L guanidine hydrochloride can cause spherical proteins to change from their natural state to the center of their transformation state. Generally, increasing the concentration value of the denaturing agent can improve the transformation level, and about 6mol/L guanidine hydrochloride can completely change the protein to its transformation state. Guanidine hydrochloride has stronger denaturation ability than urea due to its cationic properties. Some spherical proteins cannot be completely transformed even in an 8 mol/L urea solution, unaware that they generally exist in an irregularly coiled (completely transformed) conformation in an 8 mol/L guanidine hydrochloride solution.
Solubility: The solubility of urea is slower and weaker than that of guanidine hydrochloride, with a solubility of 70%~90%. When urea has a longer efficacy time or higher temperature, it cracks to produce cyanate, which decorates the hydroxyl groups of asset recombinant proteins through covalent bonds. However, it has the advantages of not being weak in electrolytes, neutralization, and low cost; Guanidine hydrochloride has a solubility of over 95% and a fast melting effect without causing covalent bond decoration of asset recombinant proteins. However, it has disadvantages such as higher cost compared to urea, easy settling under acidic and alkaline standards, and potential impact on post hoc experiments.
Overall, as common experimental reagents in protein denaturation processes, the advantages and disadvantages of guanidine hydrochloride and urea are as follows: guanidine hydrochloride has relatively strong solubility and transferability, making it less likely to cause covalent bond decoration of asset recombinant proteins. However, it has drawbacks such as increased cost, easy settling under acid-base standards, and impact on protein ion exchange chromatography analysis; Urea has relatively poor solubility, but it has advantages such as not being a weak electrolyte, being neutral, low cost, and not easily causing many proteins to settle after protein refolding. In specific experiments, scientific researchers must select based on standards and objectives to obtain the best experimental results.