Question

What is the reason Ninhydrin cannot react with Proline?
Describe the reaction of Ninhydrin with all the other amino acids

Answer 1

Ninhydrin is used to test the presence of amino acids

Ninhydrin degrades amino acids into aldehydes , CO2 and ammonia

Ninhydrin then condenses with ammonia and hydrindantin to produce a blueish-purple pigment.

This the reaction occurs with amino acids

Ninhydrin cannot react with Proline because in all other amino acids the Nitrogen is free to react with ninhydrin.

However, in proline, the Nitrogen is not available for reaction as it is locked in the ring structure. Therefore no

ammonia is produced, so no blue color is presented