BiologicalMolecules160-page20

BiologicalMolecules160-page20 - longer function This...

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Biological Molecules - 20 Protein Stability As we have seen, the physical shape of a protein is determined by the amino acid sequence and maintained by weak bonds. A mistake in the genetic coding of the amino acid sequence may result in a protein whose shape is different, and the protein will not function. One serious example of this is in the hemoglobin protein. An error in the sixth amino acid of the polypeptide chain produces a hemoglobin that causes red blood cells to become sickle-shaped rather than the normal "doughnut" shape. Many of the bonds that form the tertiary shape of proteins are hydrogen bonds formed from the polarity of the amino acids and their “R” groups. If these weak bonds are broken, the protein structure is destroyed and the molecule can no
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Unformatted text preview: longer function. This process is called denaturation. Things that can denature protein: 1. Heat (as low as 110 F, many @ 130 F) 2. Heavy metals (e.g., silver, mercury) 3. pH changes 4. Salts 5. Alcohols Ethyl alcohol least toxic 6. Many proteins will denature if placed in a non-polar substance. 7. Other chemicals Enzymes are seriously affected by denaturation – but other proteins of the body can also be denatured. Although in most cases, a denatured protein loses its function permanently, in some cases, re-naturation can occur if the substance that promotes the denaturation is removed from the protein. This is more true of chemical denaturants and particularly in experimental environments....
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