Experiment 14: Proteins And Denaturing Agents

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Experiment 14: Proteins and Denaturing Agents (adapted with permission of Dr. Ann Willbrand, USC-Aiken) Introduction Proteins are polymers of amino acids. A typical protein may be composed of hundreds of amino acids. The side chains of the amino acid residues may contain nonpolar, neutral polar, acidic, or basic groups. The primary structure of a protein is determined by the sequence of amino acids, but the secondary and tertiary structures of proteins define their natural or native states, which are often folded. This is called the native conformation and is usually the state in which the protein is most active and functional. Proteins are held in their native conformations by a combination of forces: hydrogen bonds, salt bridges…show more content…
Examine the effect of heat on the solubility of albumin B. Examine the effect of pH changes on the solubility of albumin and casein C. Examine the effects of 95% ethanol, lead(II) nitrate, silver nitrate, and tannic acid on albumin and casein Procedure A. The effect of heat Place about 1 mL of 2% albumin in a test tube and heat it in a hot water bath for a few minutes. Compare the appearance to the albumin solution at room temperature. B. The effect of pH changes Place about 1 mL of 2% albumin in each of four test tubes. Add 3 mL of water to the first. This tube will serve as a control. To the second, add 10% NaOH dropwise until the pH is 14. (To do this, add a couple of drops of NaOH to the tube; stir thoroughly with a stirring rod; then touch the stirring rod to a piece of pH paper to check your pH.) To the third, add 0.5% sodium bicarbonate solution to pH 9, and to the fourth, add 2% HCl to pH 2. Record your observations on the data sheet. Repeat the above tests using 2% casein solution. Record your observations. Compare the results for the two tests. C. The effects of ethanol, lead(II) nitrate, silver nitrate, and tannic…show more content…
Record your observations in the chart: |Medium (pH) |Effect on Albumin |Effect on Casein | | | | | | | | | |Water (pH 7) (control) | | | | | | | | | | | | | | | | | | | |10 % NaOH (pH 14) | |

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