Why proline amino acid gives yellow colour in reaction with ninhydrin?

Answer 1

Yes. Within "The Chemical Reactions of Amino Acids / Reactions of Amino Groups" there are several examples - one of which is the ninhydrin reaction. A very widely applied reaction of the alpha amino group [that is the N in the peptide bond -CCN-CCN-], it is used to estimate the quantity of amino acids [in a sample] in very small amounts.

All amino acids and polypeptides with a free alpha group react with ninhydrin and yield [or produce] an intensely purple colored product - except for Proline and Hydroxyproline {both in which the alpha amino group is termed to be 'substituted' - something to do with carbon rings} which "yield derivatives with a characteristic yellow color."

See also 'Schiff's bases'.

Answer 2

Proline reacts with ninhydrin, but in a different way. While most ninhydrin tests result in a purple color, the proline reaction is more yellow due to substitution of the alpha amino group that ninhydrin reacts with. This has to do with carbon rings.

Answer 3

Most primary amino acids give a purple colour with ninhydrin. Proline, though, gives a yellow colour.https://biochembro.wordpress.com/2013/02/18/yellow-result-from-ninhydrin-test/

Answer 4

It does react with proline, along with hydroxyproline and other alpha amino acids to form a yellow colored solution.

Answer 5

Since it's a secondary α-amino acid that doesn't have a free amino group

Answer 6

Since it's a secondary α-amino acid that doesn't have a free amino group

Answer 7

Yes, ninhydrin reagent reacts with proline. Proline and hydroxyproline yield a yellow coloured product unlike other amino acids that yield a puple colored product.

Answer 8

The yellow color in the reaction of the proline amino acid and ninhydrin is Avagadbro.

Answer 9

becoz proline is secondary amine...