Protein coloration reaction - protein yellow reaction experiment.

. Principle:
In the
protein
molecule, the benzene ring on the remnants of
amino acids
(e.g. tyrosine, tryptophan, etc.) with aromatic rings can be used to produce yellow nitro
compounds
, which can be converted into alkaline conditions Orange nitro derivatives:(Principle)
Benzene ring in residue of amino acid with aromatic ring in protein products (such as tyrosine and tryptophan) can react with nitric acid to give yellow nitro compound, which can change into saffron nitrylchin derivative in. Basic condition. The reaction is as follows:protein molecules contain amino acids with benzene rings, so yellow reactions occur. Phenylalanine is not easily nitrified and requires a small amount of thick sulfuric acid before a yellow reaction can occur.
Most proteins have amino acids with aromatic ring, they have yellow reaction. Phenylalanine is not easy to nitrify, so it is necessary to add in a little vitriol oil.

1. Protein solution (same as double-shrink reaction)
2. thick nitric acid
3.20% NaOH solution
4.0.0. 1% charcoal acid solution"Experimental operation"
1. Take 1% charcoal acid solution about 1 ml placed in the
test tube
, add 5 drops of thick nitric acid, with micro-fire carefully
heating
, observation results.
2. Take
drine
clean test tube 1, add protein sample liquid 1 ml and thick nitric acid 5 drops, precipitation, heating, do not have to boil, then precipitation becomes yellow, after cooling, to the two tubes each add 20% NaOH solution to alkaline, observe color changes, record the results and explain the phenomenon.Reagents
1. Protein solution (the same as biuret reaction
2.Aquafortis.
. 3. 20% NaOH solution
4.1% carbolic acid solution procedures
1.Take a clean and dry test tube, add 1 ml 1% carbolic acid solution and 5 drops of a quatis, then heat carefully with slow fire and observe
. 2.Take a clean and dry test tube, add 1 ml protein sample solution and five drops of aquafortis in it, and heat in the boiling water bath for five minutes. Then add 20% NaOH solution in each of the tubes, mix up. Observe color varieties, note down the results and explain them.
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