proteins: structure, function, folding key topics · proteins • chains are folded and twisted...
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Proteins: Structure, Function, Folding
– Structure and properties of the peptide bond – Structural hierarchy in proteins – Structure and function of fibrous proteins – Protein folding and denaturation – Structure analysis of globular proteins
Key topics:
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What are they made of? • What is in Protein powder? • Why?
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Amino Acids Continued…
• It is the properties of the R group that determine the property of the AA and ultimately the protein
• Hydrophobicity, polarity and charge are common measures
Primary Structure
Proteins • Contain C, H, O, plus
nitrogen
• Formed from amino acids joined together
• More than 20 amino acids can be joined in any order or number to make countless proteins (think of how many words can be made from 26 letters!)
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http://www.youtube.com/watch?v=yZ2aY5lxEGE
Protein folding
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Secondary Structure
Secondary Structure of a Protein
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Secondary Structure
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Proteins • Chains are folded
and twisted giving each protein a unique shape
• All of the bonds help maintain protein’s shape
• Shape of protein is important to its function!
Amylase Lipase
• Tertiary structure refers to the overall spatial arrangement of atoms in a polypeptide chain or in a protein
Protein Tertiary Structure
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Quaternary Structure
• Quaternary structure is formed by spontaneous assembly of individual polypeptides into a larger functional cluster
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Protein Structures
• Levels of Organization – Primary
• (the AA sequence of its polypeptide chain) – Secondary
• (H bonding between peptide bonds) – Tertiary
• (covalent, ionic, H bonding, hydrophobic)
– Quaternary • (involves more than one subunit)
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Stabilizing the Protein • pH: extremes will denature the protein • Temperature: thermal stability varies among
proteins – Typically high temp more damaging – A lot of protein purification happens at 0C or refrigerated
conditions
• Proteases and nucleases: degradative enzymes • Adsorption surfaces: many proteins denatured by
contact w/air, water, glass, or plastic
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Proteins • Provide structure
– Ex: Collagen- makes up your skin, muscles & bones
• Aid chemical activities in your body – Enzymes- work to speed up
reactions in your body
• Transport substances into or out of cells
• Help fight diseases