proteins n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Proteins PowerPoint Presentation
Download Presentation
Proteins

Loading in 2 Seconds...

play fullscreen
1 / 23

Proteins - PowerPoint PPT Presentation


  • 96 Views
  • Uploaded on

Proteins . Proteins. Multipurpose molecules. Proteins . Most structurally & functionally diverse group of biomolecules Function: involved in almost everything enzymes (pepsin, polymerase, etc.) structure (keratin, collagen) carriers & transport (membrane channels)

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Proteins' - tosca


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
proteins1
Proteins

Multipurposemolecules

proteins2
Proteins
  • Most structurally & functionally diverse group of biomolecules
  • Function:
    • involved in almost everything
      • enzymes (pepsin, polymerase, etc.)
      • structure (keratin, collagen)
      • carriers & transport (membrane channels)
      • receptors & binding (defense: antibodies)
      • contraction (actin & myosin)
      • signaling (hormones: insulin)
      • storage (bean seed proteins)
proteins3
Proteins
  • Structure:
    • monomer =amino acids
      • 20 different amino acids
    • polymer =polypeptide
      • protein can be one or more polypeptide chains folded & bonded together
      • large & complex molecules
      • complex 3-D shape

hemoglobin

growthhormones

Rubisco

amino acids

H

O

|

—C—

|

H

||

C—OH

—N—

H

Amino acids
  • Structure:
    • central carbon
    • amino group
    • carboxyl group (acid)
    • R group (side chain)
      • variable group
      • confers unique chemical properties of the amino acid

R

nonpolar amino acids

nonpolar & hydrophobic

Nonpolar amino acids

Why are these nonpolar & hydrophobic?

polar amino acids

polar or charged & hydrophilic

Polar amino acids

Why are these polar & hydrophillic?

sulfur containing amino acids
Sulfur containing amino acids
  • Formdisulfide bridges
    • cross links betweens sulfurs in amino acids

H-S – S-H

You wonderedwhy permssmelled like rotten eggs?

building proteins

peptidebond

Building proteins
  • Peptide bonds
    • linking NH2 of one amino acid to COOH of another
    • C–N bond

dehydration synthesis

protein models
Protein models
  • Protein structure visualized by
    • X-ray crystallography
    • extrapolating from amino acid sequence
    • computer modelling

lysozyme

building proteins1
Building proteins
  • Polypeptide chains
    • N-terminus = NH2 end
    • C-terminus = COOH end
    • repeated sequence (N-C-C) is the polypeptide backbone
      • can only grow in one direction
protein structure function

hemoglobin

collagen

Protein structure & function
  • Function depends on structure
    • 3-D structure
      • twisted, folded, coiled into unique shape

pepsin

primary 1 structure
Primary (1°) structure
  • Order of amino acids in chain
    • amino acid sequence determined by gene (DNA)
    • slight change in amino acid sequence can affect protein’s structure & it’s function
      • even just one amino acid change can make all the difference!

lysozyme: enzyme in tears & mucus that kills bacteria

secondary 2 structure
Secondary (2°) structure
  • “Local folding”
    • folding along short sections of polypeptide
      • interaction between adjacent amino acids
      • H bonds between R groups
      • -helix
      • -pleated sheet
tertiary 3 structure
Tertiary (3°) structure
  • “Whole molecule folding”
    • determined by interactions between R groups
      • hydrophobic interactions
        • effect of water in cell
      • anchored by disulfide bridges(H & ionic bonds)
quaternary 4 structure
Quaternary (4°) structure
  • More than one polypeptide chainjoined together
    • only then is it a functional protein
      • hydrophobic interactions

collagen =

skin & tendons

hemoglobin

chaperonin proteins
Chaperonin proteins
  • Guide protein folding
    • provide shelter for folding polypeptides
    • keep the new protein segregated from cytoplasmic influences
denature a protein
Denature a protein
  • Unfolding a protein
    • disrupt 3° structure
      • pH salt temperature
    • unravels or denatures protein
    • disrupts H bonds, ionic bonds & disulfide bridges
    • destroys functionality
  • Some proteins can return to their functional shape after denaturation, many cannot

In Biology,size doesn’t matter,

SHAPE matters!

protein structure review

multiplepolypeptides

hydrophobic interactions

aa sequence

peptide bonds

determinedby DNA

R groups

H bonds

Protein structure (review)

R groups hydrophobic interactions,

disulfide bridges