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Proteins. A look at emergent properties resulting from exquisite molecular order. Proteins: Many Functions. Proteins: Many Structures. The Amino Acid. Amino Acids. Basic structural unit = monomer COOH , NH 2 , and H atom give common structure
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Proteins A look at emergent properties resulting from exquisite molecular order
Proteins: Many Structures The Amino Acid
Amino Acids • Basic structural unit = monomer • COOH, NH2, and H atom give common structure • R-groups or side chains act as a “plug ins” with 20 different possible groups commonly found in proteins
R-groups • Divide amino acids into 4 categories: Polar, Non-polar, Acidic, Basic • Represented by three letter or one letter abbreviations (Gly,G) (Ala, A) (Ser, S) (Val, V) Non-polar Non -polar Polar Non-Polar
Polypeptides A dehydration reaction between the carboxyl end of one amino acid and the amino end of an adjacent results in a peptide bond. Note the C-C-N-C-C-N pattern that develops.
Primary Structure 1° - sequence of amino acids • Figure 5.18 - The sequence of the amino acids for lysozyme. (See The story of lysozyme)
2° - regular pattern of interactions between amino and carboxyl groups Secondary Structure Fig 5.20 -Lysozyme exhibits two secondary structures, -helix and the ß-pleated sheet.Both are due to hydrogen bonding.
Secondary Structures • Regular patterns of interaction between the C=O and the H-N of the polypeptide backbone. • Formed by Hydrogen Bonding • Two forms: -helix andß-pleated sheet
3° - Interactions between R-groups create 3D or globular structure Tertiary Structure
Quaternary Structure 4° -Interactions between two or more tertiary structures (2 or more amino acids chains)
Quiz! What kinds of kinds of interactions will these amino acids form? Cystiene (Cys, C) + Cystiene (Cys, C) HSCH3CHCOO- HSCH3CHCOO- NH3+ NH3+ HS SH
H C CH2 OH Quiz! What kinds of kinds of interactions will these amino acids form? HO C H CH2
Web Activity • Web/CD Chapter 5 - Protein Structure
Protein Modeling with pipecleaners • Brown, Blue = polar, hydrophilic • Orange, Red = non-polar, hydrophobic • Pink = Alpha helix • Green = Beta pleated sheet • Yellow = sulfhydryl group • Black = negative ionic charge • White = positive ionic charge • Note: color choices do not match picture shown