Download Biochem-5012.3B - Center for Structural Biology

Putting Proteins in Context:
The Transition From Structure to Function
Structure
(molecule)
Interaction
Interaction
System (activity)
(pathway)
 Most proteins function by binding
Factors Bound by Different Protein Classes
• Transport- O2/CO2, cholesterol, metals, sugars
• Storage- metals, amino acids,
• Immune response- foreign matter (antigens)
• Receptors- regulatory proteins, transmitters
• Structure- other structural proteins
• Enzymes- substrates, inhibitors, co-factors
• Toxins- receptors
• Cell functions- proteins, metals, ions
Surface Properties Determine What Binds
1. Steric access
2. Shape
3. Hydrophobic accessible surface
4. Electrostatic surface
Sequence and structure optimized to generate consequent
surface properties for requisite binding event(s)
Binding: Progression and Regulation
1. Allosteric Control- binding at one site effects
changes in conformation or chemistry at a point
distant in space
2. Stimulation/inhibition by control factors- proteins,
ions, metals control progression of a biochemical
process (e.g. controlling access to active site)
3. Reversible covalent modification- chemical bonding,
e.g. phosphorylation (kinase/phosphatase)
4. Proteolytic activation/inactivation- irreversible,
involves cleavage of one or more peptide bonds
Calcium Signal Transduction
Ca2+
Target