Biology 1002B Lecture Notes - Lecture 3: Heat Shock Protein, Christian B. Anfinsen, Protein Folding
Document Summary
For protein to be functional, it has to fold correctly: polypeptide chain needs to fold into native conformation. Christian anfinsen (nobel prize winner 1972) experimented with e. coli enzyme. Procedure + results: measured catalytic potential of enzyme 100, added urea to denature and unfold protein. Disrupts hydrogen bonding in polypeptide chains because it is polar itself: catalytic potential drops to zero, after removing urea, protein refolds into native conformation (90% active) Native conformation solely dependent on primary sequence. In vitro (test tube), concentrations of proteins are low around 0. 1 mg/ml. Chaperones: class of proteins, interact with and stabilize non-native forms of protein, not part of final assembly of protein(s, require energy (atp, ex. When polypeptide folds, it doesn"t try out every conformation. Energy funnelling hypothesis: when protein is in native conformation, it is in lowest energy state, note: get diagram in slide if possible. Factors that contribute to low energy: secondary structure and hydrophobic collapse.
