dimarts, 5 de gener del 2016

1.9 Protein identification

Introduction
Biuret's test is a chemical test used for detecting the presence of peptide bonds. Polypeptides as proteins, are chains of amino acids link together by peptide bonds.
A peptide bond can be broken by hydrolysis (the adding water). In organisms, protein molecules called enzymes facilitate the process.


Materials
-7x250mL beaker
-6 test tube
-Test tube rack
-6x10mL pipet
-Mortar
-Glass marking pen
-Gloves
-Goggles
-Milk
-Rice milk
-Egg
-Potato
-Distilleted water
-NaOH 20%
-10 drops of CuSO


Objectives
1. Identify peptide bonds.
2.Compare protein concentration in different foods.


Procedure

Firs of all we are going to dilute the protein
1. Add 100ml of distilled water to each 250ml beaker. Lebel them with M(milk), EW (egg white), EY (yolk), P (potato) and RM (rice milk)
2. Separate the egg white and the yolk in another beaker.
3. Smash the potato in a mortar and add some amount of the smashed potato to the P beaker.

Prepare the samples
4. Add 10ml of a dispersion of each food (M, RM, EY, EW and P) to the indicate beaker. Calculate the final concentration. All the groups will use the same dispersion from the beakers.
5. Prepare 6 test tubes (cleand and dry) and lebel (M, RM, EY, EW and P). Add 2ml of the every food dilution of each beaker.
6. Add 2ml of 20% NaOH dissolution. 
7. Shake gently and add 5 drops of CuSO4 in each tube. Allow the mixture 5 minutes. 
8. Note any colout change. Remember that proteins will turn solution pink or purple. 
9. Compare the test tubes. 

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