Protein Structure PDF

Protein Structure  Student Learning Objectives: Draw & describe the structure of an amino acid, including the central carbon, carboxyl group, amino group and side chain. Predict whether a side chain is nonpolar, polar uncharged or polar charged. Contrast hydrolysis and condensation reaction...

Protein Structure  Student Learning Objectives: Draw & describe the structure of an amino acid, including the central carbon, carboxyl group, amino group and side chain. Predict whether a side chain is nonpolar, polar uncharged or polar charged. Contrast hydrolysis and condensation reactions. Define the primary structure of a protein and identify and locate peptide bonds that maintain primary structure. Identify and contrast two types of secondary structure and identify the interactions that stabilize these structures. Identify the level of protein structure that determines the three- dimensional shape of a protein and list four types of interactions that contribute to this level of structure. Define the quaternary structure of a protein. Discuss the role of chaperone proteins in protein folding. Predict the potential consequence to protein function if the primary structure of the protein is altered. Proteins in cells: Highly diverse shapes Do the “work” of the cell Amino acids are the monomers of proteins: Carboxyl Amino Group Group Side group/chain that varies  Proteins are polymers of 20 possible amino acids. Example of a protein: Three letter abbreviations for different amino acids  Amino acids can be classified into 3 groups based on their side chains (in blue): Nonpolar Polar uncharged * Polar charged** * Polar charged side chains may have partial (d+ or d-) charge ** Polar charged side chains have full + or - charge Predict the category of each colored side chain: Connecting amino acids together – Condensation/Dehydration Reaction which removes a water molecule to connect To remove an amino acid from a protein – Hydrolysis which adds a water molecule to break  Amino acids are connected by Peptide Bonds: Why would proteins also be referred to by the name “polypeptide”?  Can you identify the location of the peptide bonds? Primary Structure of Protein: The length & sequence of amino acids in a protein  Protein polymer will undergo folding into a complex shape Based on the protein’s primary structure Several levels of folding & formation of final structure: Secondary Tertiary *Quaternary * Not all proteins have quaternary level of protein structure  Secondary Level of Protein Structure: Hydrogen bonds form along regions of the backbone of the protein polymer: b pleated sheet a Helix Within a folded protein, there can be both regions of a helices (red spirals) and b pleated sheets (blue ribbons) in addition to unstructured regions: Tertiary Level of Protein Structure: Side chains interact with other side chains within the protein: A. Hydrophobic interactions B. Hydrogen bonding C. Disulfide bridges D. Electrostatic attraction Responsible for three- dimensional structure  Quaternary Structure of Proteins: Present in functional proteins that are made up of polypeptide subunits interacting with each other Summary of Levels of Protein Folding: Primary Secondary Tertiary Quaternary Protein Folding: Proper protein folding requires chaperone proteins to guide the process: