UB HIS 401 - Chapter 5 Notes (10 pages)

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Chapter 5 Notes



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Chapter 5 Notes

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Pages:
10
School:
University at Buffalo, The State University of New York
Course:
His 401 - History of Drugs & Alcohol
History of Drugs & Alcohol Documents

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Protein Notes 10 10 2012 What determines Protein Structure Unique shape endows each protein with a specific function A Polypeptide chain of a given Amino Acid sequence can spontaneously arrange itself into a 3D shape determined and maintained by the interactions responsible for secondary and tertiary structure o Folding occurs as the protein is being synthesized in the crowded environment of the cell aided by other proteins Protein structure also depends on the physical and chemical conditions of the proteins environment o pH o Salt Concentration o Temperature o Other aspects of the environment are altered The weak chemical bonds and interactions within a protein may be destroyed causing the protein to unravel and lose its native shape o A change called denaturation This protein is misshapen the denatured protein is biologically inactive o Most protein become denatured if they are taken from an aqueous polar environment and put into a nonpolar solvent Examples ether or chloroform In these cases the polypeptide chain refolds so that its hydrophobic regions face outward toward the solvent o Other denaturing agents Chemicals Disrupt Hydrogen Bonds Disrupt Ionic Bonds Disrupt Disulfide Bridges These maintain a proteins shape Excessive heat Agitates the polypeptide chain enough to overpower the weak interactions that stabilize the structure Example Egg whites become opaque when cooked because the denatured proteins are insoluble and solidify Also explains why high fevers can be fatal Proteins in the blood can denature at very high body temperatures o Test Tube Protein Denatured protein in a test tube that has been denatured by heat or chemicals can sometimes return to its functional shape when the denaturing agent is removed The information for building specific shape is intrinsic to the proteins primary structure The sequence of amino acids determines a proteins shape o Where an alpha helix can form o Where beta pleated sheets can exist o Where disulfide bridges are



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