Skip to content
Home » Sakaguchi Test for Arginine

Sakaguchi Test for Arginine

In this Sakaguchi Test for arginine post we briefly summarise about: principle, reagents requirements, sakaguchi test for amino acids procedure, result, application and limitations of Sakaguchi Test.

The sakaguchi test for amino acids is a colorimetric biochemical test for the detection and quantification of guanidinium groups that is used as a qualitative test for arginine that is either free or in protein.

Sakaguchi Test for Arginine

Shoyo Sakaguchi, a Japanese food scientist, invented the test in 1925 and named it after him. The sakaguchi test for amino acids is an example of a colour reaction or test used to identify amino acids or proteins. The guanidinium group of arginine interacts with 1-naphthol or α-naphthol to create a coloured result in this test for arginine. Sakaguchi test for amino acids 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 for amino acids is based on the interaction of 1-naphthol with arginine’s guanidinium groups in the presence of an oxidising agent. Although the reaction’s specific mechanism is unknown, it does result in the development of a red-colored complex due to the formation of an indole-like structure. Sodium hypobromite and 1-naphthol make up the Sakaguchi reagent. The oxidising substance sodium hypobromite enhances the hydrogen bonding between two arginine molecules.

Requirements

Reagent

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

2. 40% NaOH

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

Materials

1. Test tubes

2. Test tube stand

3. Pipettes

Procedure

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

2. Then, two drops of 1-naphthol are added to the same test tube and mixed thoroughly. Now, 4-5 drops of the 10% sodium hypobromite or bromine water is added. The test tube is observed for the development of color.

Result

Sakaguchi Test

Sakaguchi Test for Arginine Reaction

Positive result: The creation of red colour indicates a positive result on the Sakaguchi’s test. This suggests that an arginine or guanidinium molecule is present.

Negative result: The absence of red colour in the Sakaguchi test indicates a negative result. This suggests that arginine or a guanidinium molecule is missing.

Applications

1. Sakaguchi test for amino acids is a biochemical test for detecting arginine in proteins, either free or mixed.

2. Sakaguchi test for amino acids is qualitative, but with the addition of urea, which stabilises the coloured result, it can be made quantitative.

Limitations

1. Because Sakaguchi’s reaction is slow, quantitative examination of the coloured result is not possible with this sakaguchi test for amino acids test.

2. Similarly, the hypochlorite may damage some of the guanidinium groups in the solution, causing problems with testing findings.

Further Readings

Reference

Join Our Telegram Channel!