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Bielkoviny , enz ýmy

Bielkoviny , enz ýmy. Július Cirák. Protein Structure. O. O. Alanine. Cysteine. C. H 2 N. C. H 2 N. OH. OH. Generic. C. C. H. H. H. H. C. C. O. Amine. Acid. H. HS. H. H. Non-polar. C. Polar. H 2 N. OH. C. O. O. Aspartic acid. ?. Histidine. R. H. C.

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Bielkoviny , enz ýmy

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  1. Bielkoviny, enzýmy Július Cirák Protein Structure

  2. O O Alanine Cysteine C H2N C H2N OH OH Generic C C H H H H C C O Amine Acid H HS H H Non-polar C Polar H2N OH C O O Aspartic acid ? Histidine R H C H2N C H2N OH OH C C H H H H C C O C H H Basic C Acid OH NH C C H+N Different Amino Acid Classes Protein Structure

  3. Levels Of Protein Organization • Primary Structure - The sequence of amino acids in the polypeptide chain • Secondary Structure - The formation of a helices and b pleated sheets due to hydrogen bonding between the peptide backbone • Tertiary Structure - Folding of helices and sheets influenced by R group bonding • Quaternary Structure - The association of more than one polypeptide into a protein complex influenced by R group bonding Protein Structure

  4. Levels Of Protein OrganizationPrimary Structure Met-Gly-Ala-Pro-His-Ile-Asp-Glu-Met-Ser-Thr-... The sequence of amino acids in the primary structure determines the folding of the molecule. Protein Structure

  5. Protein Secondary Structure • The peptide backbone has areas of positive charge and negative charge • These areas can interact with one another to form hydrogen bonds • The result of these hydrogen bonds are two types of structures: • a helices • b pleated sheets Protein Structure

  6. H N C H C H + N O C C N H O - C C N H H O O O C H N C N C OH C H O C C N H H H C H H C C C O N H H HO H H C C N C O O Protein Secondary Structure:a Helix Protein Structure

  7. H N H C C N O H + C C O N H - C C N H H O O O C H H N C N C OH C O N C C H H H C H H C C C O N H H HO H H C C N C O O Protein Secondary Structure:a Helix Protein Structure

  8. R R R R R R R R R R R R R R Protein Secondary Structure:a Helix R groups stick out from the a helix influencing higher levels of protein organization Protein Structure

  9. O O O O H H H H C C C C N N N N C C C C C C C C C C C C N N N N H H H H O O O O O O O O H H H H N N N N C C C C C C C C C C C C N N N N C C C C H H H H O O O O Protein Secondary Structure:b Pleated Sheet Protein Structure

  10. O O O O O O O O H H H H H H H H C C C C C C C C N N N N N N N N C C C C C C C C C C C C C C C C C C C C C C C C N N N N N N N N H H H H H H H H O O O O O O O O O O O O H H H H N N N N C C C C C C C C C C C C N N N N C C C C H H H H O O O O Protein Secondary Structure:b Pleated Sheet Protein Structure

  11. Levels Of Protein OrganizationTertiary Structure • Tertiary structure results from the folding of a helices and b pleated sheets • Factors influencing tertiary structure include: • Hydrophobic interactions • Hydrogen bonding • Disulphide bridges • Ionic bonds Protein Structure

  12. e.g. haemoglobin 3º structure normally folds up in a ball hydrophilic R groups point outwards Hydrophobic R groups point inwards soluble metabolic functions e.g. collagen 2º structure does not fold up, form fibres not surrounded by hydrophilic R groups insoluble structural functions Globular and Fibrous Protein Structure

  13. O O Glycine Valine C C H2N H2N OH OH C C H H H H C CH3 H3C O Proline H2N+ C OH H2C C H H2C CH2 Hydrophobic interactions Protein Structure

  14. O Glutamine C H2N O OH Asparagine C H C H2N OH H C H C H H C H C O C H O C H NH2 NH2 Hydrogen Bonding N-------H (+) (-) O -------C slightly slightly Protein Structure

  15. O O O O C C C C H2N H2N H2N H2N OH OH OH OH C C C C H H H H Cysteine Cysteine Cysteine Cysteine H H H H C C C C S S HS HS H H H H Disulphide bridges Protein Structure

  16. O Arginine Glutamic acid C H2N OH C H H C H O H C H H C C H2N OH H N C H +H2N H C H C H NH2 H C O C H O- Ionic Bonds Protein Structure

  17. e.g.G-3-P DehydrogenaseTertiary Structure Picture source: SWISS-PROT Protein Structure

  18. Collagen is a fibrous protein made of 3 polypeptide helices held together by hydrogen bonding • Every 3rd amino acid in the chain is a glycine (very small to let the chains lie close to each other) • Collagen molecules are found side by side forming fbres • The staggered ends help to give collagen fibres great tensile strength Protein Structure

  19. Levels Of Protein OrganizationQuaternary Structure • Quaternary structure results from the interaction of independent polypeptide chains • Factors influencing quaternary structure include: • Hydrophobic interactions • Hydrogen bonding • The shape and charge distribution on amino acids of associating polypeptides Protein Structure

  20. Haemoglobin Picture source: SWISS-PROT Protein Structure

  21. a b Fe b a Haemoglobin • Haemoglobin is a globular protein with a prosthetic ‘iron’ group • In adults, hemoglobin is made up of 4 polypeptides (2 a polypeptide chains and 2 b polypeptide chains) • Each polypeptide surrounds a prosthetic ‘haem’ group • Hydrophobic interactions between side groups pointing inwards maintain the structure • Hydrophilic side chains point outwards making it soluble Protein Structure

  22. G-3-P Dehydrogenasefrom Bacillus stearothermophilus Protein Structure Picture source: SWISS-PROT

  23. Sickle Cell Anaemia Protein Structure

  24. E + S → ES → EP → E + P

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