What is Sakaguchi's Test?

 







Experiment # 7

 

 

 

 

SAKAGUCHI’S TEST



 

 

Sakaguchi test is a biochemical test consisting of colorimetric reaction for the detection and quantification of guanidinium groups, used as a qualitative test for arginine that is either free or in protein. The test was discovered by and named after the Japanese Food Scientist Shoyo Sakaguchi

in 1925. Sakaguchi test is an example of color reactions or test that is performed for the detection of amino acids or proteins. The test is a specific test for arginine where the guanidinium group of

arginine reacts with 1-naphthol or α-naphthol to produce a colored product. It is a qualitative test, and the quantification of arginine is hindered in this test due to the slow rate of color development and destruction of some guanidinium groups by the reagent.

 

 

Principle 

 

❖  Sakaguchi test is based on the principle of reaction between 1-naphthol and the guanidinium groups in arginine, in the presence of an oxidizing agent.

❖  The Sakaguchi reagent consists of sodium hypobromite and 1-naphthol. The sodium hypobromite acts as an oxidizing agent that facilitates the hydrogen bonding between two arginine molecules.


   

 

 

Requirements for Sakaguchi’s test: 

 

 

 

 

Reagent:

 

Sakaguchi reagent: 1% 1-naphthol in alcohol with a few drops of 10% sodium hypobromite solution of bromine water. % NaOH

Sample (0.1% of arginine or 0.1% of creatine).

 

❖   

❖  40

❖   

 

 

 

 

.

Materials required:

 

PROCEDURE 

About 3 ml of the test solution is added in a test tube, to which 1 ml of 40% NaOH is added and

-naphthol are added to the same test tube and mixed thoroughly.

 drops of the 10% sodium hypobromite or bromine water is added.

The test tube is observed for the development of color

 

•      Test tubes

•      Test tube stand

•      Pipettes

µ   

mixed correctly.

µ  Then, two drops of 1

µ  Now, 4-5

µ   

 

 

 

 

RESULTS

 

 

 

 

 

 

 

Observation:

 A positive result on the Sakaguchi’s test is demonstrated by the formation of red

color. This indicates the presence of an arginine or guanidinium compound.

Sakaguchi’s Test is a biochemical test for the detection of arginine in the free or combined

.

Quantitative analysis of the colored product is not possible with this test as the rate of Sakaguchi’s reaction is slow.

Similarly, some of the guanidinium groups in the solution might be destroyed by the hypochlorite, resulting in difficulties in testing results..

 

 

 

Uses:

 

form in proteins

 

•

 

Limitations:

 

 

•          

•          

 

 





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