4.Folin's method for quantitative determination of proteins (by phenol reagent)

Question 1

which 2 important proteins in this reaction react with the Folin’s reagent?

Answer 1

tyrosine and tryptophan

Question 2

what is the color of the product in the folin’s method?

Answer 2

blue

Question 3

why is the color of the product blue?

Answer 3

due to the reduction of phosphomolybdate and -tungstate into molybdateblue and tungstateblue.

Question 4

the intensity of this color depends on?

Answer 4

the amount of tyrosine and tryptophan present in a particular protein

Question 5

in which dilution concentration the Folin’s method can be used?

Answer 5

200-500 mg of protein in 1 l of protein solution

Question 6

folin’s reagent 1?

Answer 6

Stock solutions:
\A.CuSO4(0.06mol/l)
B. Seignette-salt (0.07 mol/l)
C. Na2CO3 (0.19 mol/l; dissolved in 0.1 mol/l NaOH)

Question 7

which commercial reagent do we use in the folin’s reagent 2?

Answer 7

solution of phosphoric tungstate, phosphoric molybdate and lithium sulphate in hydrochloric acid.

Question 8

what will be the color of the product of folin’s method?

Answer 8

blue

Question 9

at what absorbance will be the product of folin’s method?

Answer 9

750 nm

Question 10

The intensity of the blue color in the folins method depends on…

Answer 10

The amount of the 2 aromatic amino acids (tyrosine and tryptophan) in a particular protein