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    Home > Biochemistry News > Biotechnology News > The Folin-Phenol Reagent Method (Lowry Method) measures protein concentration.

    The Folin-Phenol Reagent Method (Lowry Method) measures protein concentration.

    • Last Update: 2020-10-25
    • Source: Internet
    • Author: User
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    the principle of
    lowry method for determining the
    concentration
    proteins in the united States.

    protein in alkaline solution its peptide bonds and Cu
    2 plus
    chelate, forming a protein copper complex, this compound makes phenol
    reager
    phosphoric acid reduction, the production of blue
    compound
    , under certain conditions, using the blue depth and protein concentration linear relationship as a standard curve and determine the concentration of protein in the sample.


    test tubes
    7, number, press the table operation:
    immediately mix, in 20 degrees C to 25 degrees C water bath insulation for 30 minutes. The light density value was determined by using 660nm color ratio.operational precautions:1. Add reagents in order
    2. Reagent b is stable under acidic conditions, alkaline conditions (reagent A) is easy to be destroyed, so add reagent B immediately after mixing, plus a tube mixing a tube, so that reagent B (phosphoric acid) before destruction is reduced.the standard(i) by using the calculation. The standard curve is drawn with the concentration as the horizontal coordinate and the light density value as the ordinate.
    (ii) to determine the light density value of the tube, find the standard curve, find the protein concentration (g/L
    in the
    serum to be tested.
    (iii) and then select from the standard tube - the tube and the measurement tube light density close to the person, to find out the protein concentration in the serum to be tested (g/L).equipment (i) 721 type hydrometer
    (-)
    thermostat
    water bath
    (iii) test tube 7
    (iv) scale straw: 1. 0ml two; 0.5ml one; 5.0ml one.(i) Reagent meth
    (1) 4% sodium carbonate (Na
    2
    CO
    3
    ) solution
    (2)0.2N sodium hydroxide solution
    (3) 1% copper sulfate solution (CuSO

    4
    5H
    2
    O)
    (4) 2% potassium sodium sodium solution (or potassium or sodium citrate)
    before use (1) and (2), (3) and (4) volume mix, and then mix the two mixtures in 50:1 ratio, that is, reagent armor. The reagent can only be used for one day and expires.
    (i) Reagent B:
    (1) commercially available phenol reagents are titration with NaOH before use, with phenolic peptides as the indicator agent, which is diluted according to the acidity of the reagent, so that the final acidity is 1N.
    (2) or take na
    2
    WoO
    4
    2H
    2
    O l00g and Na
    2
    MOO
    3
    25g. Dissolved in distilled water 700 ml, add 85% H
    3
    PO
    4
    50ml and HCl (thick) 100ml, mix the upper contents, put 1000 ml round bottom burner gently reflow for 10 hours, and then add lithium sulfate (Li2SO4H2O) 150g, water 50ml and bromine drops. Continue to boil for 15 minutes to remove the remaining bromine, cool down to 1000ml and then
    filter
    , the solution should be yellow or golden (if not available with green), stored in a brown bottle, used with standard NaOH titration, phenolic as an indicator, and then diluted about twice, so that the final acidity of 1N.
    (iii) standard protein solution
    a protein solution of 0.25 mg/ml is made from crystalline bovine serum albumin and distilled water according to its purity. (Purity can be determined by the Kye's nitrogen determination method to determine the protein content).
    (iv) Samples to be tested: accurate serum 0.1 ml, placed in 50 ml
    capacity bottle
    , plus 0.9% NaCl solution to the scale, fully mixed, can also use urine as a sample.
    .
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