Chapter
3: PROTEIN STRUCTURE & FUNCTION
Amino acids and protein structure:
- Structural
groups of amino acids (3-2); primary structure of proteins (3-3);
secondary structures (a -helix, b sheet, random coil) (3-6,3-8);
tertiary structure - motifs of secondary structures (3-9); disulfide bonds
(3-13); quaternary structure (3-4).
- Protein
folding (3-14); Chaperones promote proper folding (3-15).
- Protein
degradation; extracellular degradation by digestive proteases; lysosomal
pathway; ubiquitin mediated proteolysis (3-18).
Protein function:
- Function
generally depends on binding of to ligands; binding is dependent on
affinity and specificity.
- Enzyme
function — catalysis of reactions that convert substrates to products;
active site and catalysis by stabilizing the transition state (3-23,
3-24); catalysis is described by the affinity of an enzyme for substrate
(Km) and the maximal velocity of a reaction in saturating
amounts of substrate (Vmax).
- Regulating
protein function; allosteric release of catalytic subunits (3-27);
allosteric transition between active and inactive states (3-28);
cooperative binding of ligands (hemoglobin binding to oxygen); phosphorylation;
proteolytic activation (3-31).