ACITIVITY 2AQUALITATIVE TEST FOR PROTEINS/COLOR REACTION TEST

GROUP 6 BMLS – 2HMARIMON, Dave Michael C. April 21, 2014MACION, Ayn Rand Louise V.TANDUYAN, Maria CristaliaRUIZO, Roichinne DATUMANONG, Madatu Datudick Jr.BAID, Ivy ZeaMALIRONG, Chiezyl

OBJECTIVES:

To detect proteins through the different color reaction tests. To know the significance of peptide bonds and amino acids in detecting proteins. To understand the principle behind every test.

RESULTS AND OBSERVATION:

NAME OF TEST SUBSTANCE TO BE TESTED

REAGENTS USED VOLUME OF REAGENTS USED

OBSERVATIONS/RESULTS

Millon’s Test Proteins Millon’s Reagent 2 drops The solution DOES NOT have flesh precipitate to red color. NEGATIVE ( - )

Xanthoproteic Test Proteins Concentrated Nitric Acid

Ammonium Hydroxide

5 drops

5 drops

The solution is cloudy color yellow with residue remained. POSITIVE ( + )

Glyoxylic Acid Reactions

(Hopkins – Cole)

Proteins Hopkin’s Cole Reagent

Pure Concentrated Sulfuric Acid

1 mL

10 dropsThe solution DOES NOT have a violet ring that will form between the 2

liquids. NEGATIVE ( - )

Biuret Test Proteins 10% Sodium Hydroxide

0.5% Copper Sulfate

1 mL

1 mL

The solution is clear blue and violet.POSITIVE ( + )

Ninhydrin Test Proteins 0.1% aqueous solution of Ninhydrin

1 mL The solution DID NOT produce a blue color. NEGATIVE ( - )

Sakaguchi Reaction for Arginine

Proteins10% Sodium

Hydroxide

Diltute Alcoholic a-naphthol solution

Sodium Hypobromite Solution

1 mL

6 drops

10 drops

The solution DID NOT produce a red color. NEGATIVE ( - )

PROOF/DOCUMENTATION:

A B C D E F

FROM LEFT TO RIGHT:A. MILLON’S TESTB. XANTHOPROTEIC TESTC. GLYOXYLIC ACID REACTIONS (HOPKINS – COLE)D. BIURET TESTE. NINHYDRIN TESTF. SAKAGUCHI REACTION FOR ARGININE

ANALYSIS AND CONCLUSION: GUIDE QUESTIONS

1. Explain the principle involved in each of the test for proteins.

Millon’s test - Millon’s reagent gives the positive results with proteins containing the phenolic amino acid ‘tyrosine”, the precipitate turns flesh red color, proteins containing tyrosine are present.

Xanthoproteic test - Determined the amount of the protein soluble in a solution using the concentrated Nitric acid. The test gives the positive result in those proteins with amino acid carrying aromatic groups especially tyrosine. The proof is neutralized with an alkali, turning dark yellow.

Hopkins’ Cole test - There was a violet color produced at the point of contact. Tryptophan has an in dole nucleus which is responsible for the violet ring found at the junction between the two layers.

Biuret test - Reduction of Cu2+ which then complexes with the N atoms on the peptide bonds at high Ph.

Ninhydrin test - Amino acids containing a free amino group and a free carboxylic acid group that react together with ninhydrin to produce color products. Group on the alpha- carbon and can react with ninhydrin to produce blue purple product.

Sakaguchi test - In alkaline solution, protein containing Arginine gives red color with Alpha-Napthol and Sodium hypochloride.