7/23/2019 Exp4Protein Determination (Lowry) (1)

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UNIKL MICET

CFB 20203 FOOD BIOCHEMISTRY 

1

EXPERIMENT 4: Lowry Assay Protein Assay

The Lowry procedure is one of the most venerable and widely-used protein assays, being firstdescribed in 1951 [Lowry et al., J. Biol. Chem. 19! "#5-"$5 %1951&'. (nder al)aline conditions,

copper comple*es with protein. +hen folin phenol reagent %phospho-molybdic-phosphotungsticreagent& is added, the olin-phenol reagent binds to the protein. ound reagent is slowly reduced

and changes color from yellow to blue.

il) contains ./ total protein. il) proteins contain all 9 essential amino acids re0uired by

humans. il) proteins are synthesied in the mammary gland, but #2/ of the amino acids used

to build the proteins are obtained from the cow3s diet. Total mil) protein content and amino acidcomposition varies with cow breed and individual animal genetics.

4bective!

To estimate the amount of protein in un)nown sample by Lowry6s method

Materials Required

Reagents Required:

7. "/ 8a"4 in 2.1 8 8a4:

. 1/ 8a; Tartrate in :"4

. 2.5/ u<4=. 5:"4 in :"2

>. Reagent I! =? mL of 7, 1 mL of , 1 mL

@. Reagent II- 1 part olin-Ahenol [" 8'! 1 part water 

<7 standard- 1 mgBmL

il)

Procedure:

1. 2." mL of <7 wor)ing standard in 5 test tubes and ma)e up to 1 mL using distilledwater.

". The test tube with 1 mL distilled water serves as blan).

LAB MANUAL

7/23/2019 Exp4Protein Determination (Lowry) (1)

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UNIKL MICET

CFB 20203 FOOD BIOCHEMISTRY 

2

. 7dd =.5 mL of Ceagent D and incubate for 12 minutes.

=. 7fter incubation add 2.5 mL of reagent DD and incubate for 2 minutes.

5. easure the absorbance at ##2 nm and plot the standard graph.

#. @stimate the amount of protein present in the given sample form the standard graph.

LAB MANUAL