Protein estimation by Biuret Test

Heya lovelies

So chemical estimations have been my favorite in practicals. Hence today we will be discussing estimation of proteins by Biuret test. Biuret test can be used as a qualitative or quantitative method for protein estimation.

Lets first understand what is qualitative and quantitative.

Qualitative - whether the particular compound is present or no.

Quantitative - if present, then how much.

Biuret reagent is prepared with sodium hydroxide and hydrated copper sulphate with potassium sodium tartarate.

Mnemonic: Katy Perry danced to a Pole Song.

Standard used - Bovine Serum Albumin (BSA).

Proteins tend to bind Cu ions in alkaline conditions to form copper chelate in basic pH, which is blue in color. This color is measured at 540 nm in a colorimeter. Potassium sodium tartarate is known to stabilize Cu ions.

Biuret estimation though is very accurate, is not sensitive enough. it cannot measure proteins concentration below 100 mcg.

Folin Lowry is an alternative method used for lower protein containing samples.

That's all.

Hope it helps you learn.

-Staph <3