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The Structure of Proteins

The Structure of Proteins

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The Structure of Proteins

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  1. The Structure of Proteins

  2. Functions of Proteins • Fibrous proteins – structural, e.g. collagen. • Globular proteins – metabolic functions, e.g. haemoglobin. • It is their structure that allows them to carry out their functions.

  3. Structure of Proteins • Monomer units of proteins are called amino acids.

  4. Structure of Proteins Amino Acids C

  5. Structure of Proteins Amino Acids AMINO GROUP H C N H

  6. Structure of Proteins Amino Acids AMINO GROUP O H H C C N O H CARBOXYLGROUP

  7. Structure of Proteins Amino Acids AMINO GROUP O H H C C N O H CARBOXYL GROUP

  8. H Structure of Proteins Amino Acids AMINO GROUP O H H C C N O H CARBOXYL GROUP

  9. Structure of Proteins Amino Acids H AMINO GROUP O H H C C N O H CARBOXYL GROUP

  10. Structure of Proteins Amino Acids H AMINO GROUP O H H C C N O H CARBOXYL GROUP R-GROUP (Variant)

  11. Structure of Proteins Amino Acids H AMINO GROUP O H H C C N O H CARBOXYL GROUP R-GROUP (Variant)

  12. Structure of Proteins PRIMARY STRCUTURE – Polypeptides • Polypeptides are composed of amino acids bonded to each other, like beads on a string • The bond that holds them together is called a peptide bond • They are formed by loss of water so is called a condensation reaction.

  13. Structure of Proteins PRIMARY STRCUTURE – Polypeptides

  14. Structure of Proteins PRIMARY STRCUTURE – Polypeptides • -OH from carboxyl group • -H from amino group • Forms peptide bond

  15. Structure of Proteins Secondary Structure – α helix +ve -ve

  16. Structure of Proteins Tertiary Structure – α helix • 3D structure is formed by further bonds, depending on the function • Disulphide bonds – strong and not easily broken down • Ionic bonds – easily broken down by changes in pH (carobxy/amino groups) • Hydrogen bonds – numerous be very easily broken down

  17. Functions of Proteins • Fibrous proteins – structural, e.g. collagen. • Globular proteins – metabolic functions, e.g. haemoglobin. • It is their structure that allows them to carry out their functions. • i.e. the 3D structure is v.v.v important in carrying out it’s function • Makes proteins distinctive – interacting with other molecules

  18. Structure of Proteins Quaternary Structure • Complex molecules containing many polypeptide chains

  19. Structure of Proteins Example – haemoglobin:

  20. Test for proteins