Protein estimation in biological and non-biological fluids
Among the various methods of protein estimations, Lowry's modified method is the most efficient. It can be used to measure proteins as low as 1 microgram per ml.
The method is Lowry's method of protein estimation. The copper protein complex reduces the mixture of phosphomolybdate-phosphotungstate present in Folin reagent.
This gives blue color complex. The intensity of blue color depends on the concentration of protein.
Reagent A: 2% sodium carbonate, 0.1 N NaOH.
Reagent B: 0.5% Copper Sulphate pentahydrate, 1% sodium potassium tartrate.
Reagent C: Mix 50 ml of Reagent A and 1 ml of reagent C. (Always use fresh solution)
Reagent D: it is commercially available as 2N solution. For use in this test is to be duluted 1:1 (Just before use)
Protein Standard solution: Bovine Serum Albumin (BSA) 1mg per ml.
Prepare Standard Solution:
Take 1 ml of diluent as a blank.
Around 1 hour.
The Protein solution mixed with SDS, Tris, EDTA, thiol reagent, potassium, magnessium, etc. do not reliable results in this test.
This compounds are to be removed by precipitation of protein with 10% trichloroacetic acid. And finally redissolve the protein pellet in 2N NaOH solution.
The folin reagent must be stored in 4 deg C. A good quality reagent is straw yellow in colour.
The colour of protein solution at the end of test is blue in color. If the color is not blue the test should be repeated.
Folin. O and Ciacalteu, C. 1927. Journal of Biological Chemistry. 73: 627.
Lowry, OH, Rosebrough NJ, and Randall, RJ. 1951. Journal of Biological Chemistry. 193:265.
Comments can take the form of short reviews, notes or questions to the author. Comments will be posted immediately. If reported by the community, we will temporarily hide the comment to determine if the comment is spam or harassment. If it is not, it will be unhidden, and it cannot be reported again. If you think a comment has been hidden or unhidden mistakenly, please contact us at [email protected].
Posted 17 Mar, 2015
© Research Square 2020