The buffer range of Tris is about 6-8, which is suitable for most biochemical experiments, especially in the related research experiments of protein and nucleic acid; EPPS is also suitable for protein and nucleic acid. The research experiment is more expensive than Tris, so which one is suitable for the Folin phenol method to detect protein experiment?
The Folin-phenol reagent method is a basic method commonly used to determine protein concentration and has been widely used in the field of biochemistry. In practical applications, EPPS (HEPPS) is usually used as a buffer for Folin phenol method to detect protein content, rather than using Tris buffer.
Buffer Tris and EPPS are used for protein content detection
The coloring principle of the Folin phenol method for the determination of protein content is the same as that of the biuret method (but EPPS cannot be used for biuret/biuret detection). The difference is that the second reagent, the Folin-phenol reagent, is added. In order to increase the amount of color, thereby improving the sensitivity of detecting proteins. The advantage of the Folin phenol method for detecting protein content is that it has high sensitivity and is much more sensitive than the biuret method. Of course, it also has some disadvantages that it takes a long time, the standard curve is not straight, the specificity is poor, and there are more interfering substances.
Any group that interferes with the biuret reaction, such as -CO-NH2, -CH2-NH2, CS-NH2 and Tris buffer, sucrose, ammonium sulfate, and sulfhydryl compounds, can interfere with the Folin-phenol reaction and affect the latter Much bigger. In addition, phenols and citric acid also interfere with this reaction.
Folin-phenol reagent consists of two reagents. Reagent one consists of sodium carbonate, sodium hydroxide, copper sulfate and potassium sodium tartrate. The peptide bond in the protein reacts with the potassium sodium copper tartrate solution under alkaline conditions to form a purple-red complex. The second reagent is composed of phosphomolybdic acid, phosphotungstic acid, sulfuric acid, bromine and so on. Under alkaline conditions, this reagent is easily reduced by the phenolic group of tyrosine in the protein to give a blue reaction, and its color depth is proportional to the protein content. This method is also suitable for determining the content of tyrosine and tryptophan. The measurement range of this method is 25-250μg protein.
In summary, the advantage of the Folin phenol method for determining protein content is high sensitivity, but the disadvantage is that it takes a long time and interferes. Tris can also cause interference. EPPS buffer should be used. Desheng produces both of these buffers, not to say which one is better, but to be suitable for different experimental studies.
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