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100 Noyes AQD,AQE,AQF Yuan AQA,AQL Sedlacek AQI,AQK Smith. 62 Krannert Art Museum AQB,AQC Park AQN Gupta AQG Phelan. Final Exam – 104A Monday, May 10 8:00 – 11:00 am. 100 Noyes CQD,CQE,CQK Dokukin CQG,CQK Brea. 228 Natural History Bldg. CQA,CQC Randeria CQB,CQP Phelan
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100 Noyes AQD,AQE,AQF Yuan AQA,AQL Sedlacek AQI,AQK Smith 62 Krannert Art Museum AQB,AQC Park AQN Gupta AQG Phelan Final Exam – 104A Monday, May 10 8:00 – 11:00 am
100 Noyes CQD,CQE,CQK Dokukin CQG,CQK Brea 228 Natural History Bldg. CQA,CQC Randeria CQB,CQP Phelan CQI,CQJ Loman Final Exam – 104C Friday, May 14 7:00 – 10:00 pm
Amino acids R-groups non-polar polar acidic basic proteins condensation between carboxylic acids and amines + + H2O carboxylic acid amide amine
Amides resonance structure amides dipeptide glycine alanine Ala-Gly +H2O
H H H _ _ _ = = = O O O R R R _ _ _ Polypeptides “backbone” _ H N1- C1- C1- N2- C2- C2- N3- C3- C3- OH peptide bonds C-terminal residue N-terminal residue biological activity = structure 4 levels protein structure
Primary structure sequence of amino acids hemoglobin transports O2 and CO2 300 amino acids 4 protein chains Sickle cell anemia 6thamino acid from N-terminus Glu R Val -CH2CH2-CO2H -CH(CH3)2 water soluble water insoluble
H H H _ _ _ _ H N1- C1- C1- N2- C2- C2- N3- C3- C3- OH = = = O O O R R R _ _ _ Secondary structure hydrogen bonding backbone groups H-bond donors H-bond acceptors -helix Two main secondary structures: -sheet
H C N = O C = O Alpha helix Every C=O bonded to N-H 4 residues away forms a helix core is backbone R-groups outside 3.6 amino acids per turn proline no H-bonding breaks helix
Beta sheet Every C=O bonded to N-H far apart in 1o structure on different chains peptide chains extended side-by-side maximal H-bonding for anti-parallel chains small R-groups above and below the sheet if not -helix or -sheet random coil
Fibrous Proteins 1o structure amino acid sequence - helix -sheet H-bonding between C=O and N-H of backbone 2o structure + - some proteins only have 1o and 2o structure: fibroin (silk) -sheet insoluble in H2O hair skin - helix keratin collagen non-polar residues
H H H H C C N N N N C C C C C C S S Disulfide bonds cysteine -CH2-SH S-H H-S reduced [O] oxidized
Tertiary structure Primary structure sequence of amino acids Ala-Phe-Ser-Ser-Val-Glu-His-Ile-Met-Arg-Asp-Val-His-Asn-Gly Phe- Ser- Ser- Val- Glu- His- Ile- Met- Arg- Val- His- Asn- Gly- Asp- Ala- Non-polar Polar Acidic or Basic Alanine Serine Glutamic acid Phenylalanine Histidine Arginine Valine Aspartic acid Isoleusine Asperagine Methionine Glycine
11 4 7 15 Asp Ser His Gly 3 8 Ser Ile Val 14 Asn 12 Arg 10 Ala 1 Glu Val 5 6 Phe Met His 2 9 13 Tertiary structure Ala-Phe-Ser-Ser-Val-Glu-His-Ile-Met-Arg-Asp-Val-His-Asn-Gly arrange these in an -helix polar non-polar interior exterior
- + - - - + + - Tertiary structure interaction of the R-groups globular proteins proteins fold around non-polar groups hydrophobicresidues inside polar and charged residues outside
Tertiary structure interactions of R-groups non-polar R-groups 1. Hydrophobic interactions LDF polar R-groups 2. Hydrogen bonding between H-bond donors and acceptors 3. Ionic bonds (salt bridges) acidic and basic R-groups ion-ion (disulfide) cysteins 4. Covalent bonds
His Ala Phe Arg Asp Cys Cys His CH3 S -O-CH O NH+ = S C-terminus Fe2+ N-terminus Pro Pro