Proteins

Slide 2 of 19 Proteins  Polymers composed of amino acids  Protein = Polypeptide (polymer)  Monomer = Amino acids  Peptide bonds  Amino acid  Amine Group (NH2)  Basic  Carboxylic Acid Group (COOH)  Acidic

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Slide 4 of 19 Protein Functions

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Slide 6 of 19 4 Levels of Protein Structure  Primary level  Sequence of amino acids  Polar covalent bonds link the amino acids  Only level that doesn’t use hydrogen bonds  Secondary  Hydrogen bonding between amino acid side groups  The sequence of amino acids converts into 1 of 2 forms  α-helix  β-pleated sheets

Slide 7 of 19 1’ and 2’ Levels Protein Structure

Slide 8 of 19 1’ & 2’ Animations  05_21aPrimaryStructure.swf  05_21bSecondaryStructure.swf

Slide 9 of 19 3’ & 4’ Structure  Tertiary  3D shape of a polypeptide  Many types of bonds/interactions between side groups  Disulfide bridges are most significant here  Quaternary  2 or more polypeptides (subunits) of a protein  Not found in all proteins  Same bonds/interactions as tertiary level

Slide 10 of 19 Tertiary & Quaternary Levels

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Slide 12 of 19 3’ & 4’ Animations  05_21cTertiaryStructure.swf  05_21dQuaternaryStructure.swf  Animation swf

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Slide 15 of 19 Protein Denaturation

Slide 16 of 19 Protein Denaturation  Denaturation  Protein unravels and loses its native conformation  Structure & Function  Change in the protein’s structure = loss of function  Denaturation occurs:  Organic solvent  Any chemical that disrupts the tertiary structure  Heat (excessive)

Slide 17 of 19 Chaperonins  Proteins that assist the proper folding of other proteins  Provide stable, insulated environment for polypeptide to achieve the correct conformation

Slide 18 of 19 Protein Questions  Name all of the bonds in primary protein structure?  What bonds hold together secondary structure?  What about tertiary level? Quaternary?  Which level of protein structure is NOT found in all proteins?

Slide 19 of 19 Protein Questions (Page 2)  What is the name of a protein’s monomer?  What is the name of a protein’s polymeric form?  What are the 2 functional groups on an Amino Acid?