Proteins

Proteins

1. Purpose

   • building blocks
   • chemical reaction execution (enzymes)
   • Channels and pumps
   • Cells signals
   • Molecular machines (motor proteins, myosin)
   • Other
     • antibodies
     • hormones
     • toxins

2. Structure

   • Primary
     • Amino Acids
       • 20 types!
     • Peptide bonds
       • Partial double bond character
       • No free roation
         • Dihedral/torsion angles
           • omega/phi/psi
           • Ramachandran Plot
       • Trans > cis
         • X-X 1000:1
         • X-Pro 4:1
   • Folding
     • Polarity
       • Polar side chains exposed
       • Non-polar side chains buried in core
     • Turns
       • Gly and Pro
     • Forces
       • Electrostatic
         • Point charges
         • Dipoles
       • VdW forces
       • Hydrogen Bonds
         • 2 electronegative atoms
         • Dipole D-H interacting with partial neg A
       • Hydrophobic interactions
         • Driven by entropy
         • Creates more stable state
     • Cooperative and Revesible
     • Chaperones
       • Avoid misfolding
       • fights:
         • Molecular crowding
         • Nascent polypeptides
   • Secondary
     • Alpha helix
     • Beta sheet
       • Beta turns
     • Super secondary structure
   • Tertiary
     • fold of protein chain
   • Quaternary
     • arrangement of subunits