What Are the Different Methods of Protein Concentration Determination?

The normal human body value is generally 60-80 g / L.

The determination of protein concentration is to determine the concentration of protein by chemical or physical methods. It is an important method often used to calculate the recovery of purification methods.

Name: Protein concentration determination

category: blood

Normal protein concentration determination

The normal human body value is generally 60-80 g / L.

Clinical significance of protein concentration determination

Abnormal results: (1) Biuret method: Biuret method is the first method to determine protein concentration by colorimetric method. Ammonium sulfate does not interfere with color development, peptide bonds between Cu2 + and protein, and tyrosine residues. Combined to form a purple-blue complex, which has a maximum absorption at a wavelength of 540 nm. The biuret method is commonly used for determination of protein solutions with a content of 0.5g / L-10g / L. (1) Lowry method: Cu + forms a complex with protein in an alkaline solution, and then this complex reduces the phosphorus molybdenum phosphorus-phosphotungstic acid reagent (Fulin-phenol reagent), resulting in a dark blue substance. This method is much more sensitive than the biuret method and is suitable for determination of protein solutions with a content of 20mg / L-400mg / L. (1) Ultraviolet absorption method: Most proteins have a characteristic maximum absorption at a wavelength of 280 nm, which is due to the presence of tyrosine, tryptophan, and phenylalanine in the protein, which can be used to determine the content of 0.1-0.5mg / ml Protein solution. People to be checked: People with weakness, fatigue, drowsiness, pale skin and mucous membranes, and inattention.

Precautions for protein concentration determination

Unsuitable people: people with obvious bleeding tendency. Contraindications before the test: Do not eat too greasy, high-protein food the day before the test, and avoid drinking a lot. The alcohol content in the blood directly affects the test results. After 8 pm the day before the physical examination, you should fast. Requirements during the examination: You should relax when taking blood to avoid contraction of blood vessels due to fear and increase the difficulty of collecting blood. In the determination, a small part of the protein-dye complex was adsorbed on the wall of the cuvette, and the experiment proved that the adsorption amount of the complex was negligible. After the measurement, the blue cuvette can be washed clean with ethanol.

Protein concentration determination check process

(1) The standard curve of the standard method is to take 14 test tubes, and divide them into two groups and operate in parallel according to the following table a. Draw a standard curve: Use A595nm as the ordinate and the standard protein content as the abscissa. Draw a standard curve on the coordinate paper. (2) Formulate a standard curve for the micro method. Take 12 test tubes, and divide them into two groups to operate in parallel as shown in Table b. Draw a standard curve: Use A595nm as the ordinate and the standard protein content as the abscissa. Draw a standard curve on the coordinate paper. (3) The measurement method for the protein concentration of the unknown sample is the same as above. Take an appropriate unknown sample volume so that the measurement value is within the straight line range of the standard curve. Based on the measured A595nm value, the amount equivalent to the standard protein was found on the standard curve, and the protein concentration (mg / ml) of the unknown sample was calculated.