Protein Structure III - Kevin Ahern's BB 450 Lecture #5 2016

1. Tertiary structure arises from interactions between amino acids distant in primary sequence. 2. Forces stabilizing tertiary structure include disulfide bonds, hydrogen bonds, ionic interactions, metallic bonds, and hydrophobic interactions. Disulfide bonds are the strongest forces holding tertiary structure together. 3. Most proteins that are in cells are globular. 4. In folded proteins found in aqueous environments amino acids tend to be on the outside of the protein and hydrophobic amino acids tend to be on the inside. 5. A protein with tertiary structure typically contains mulitiple secondary structures. 6. Random coils are distinguished from reverse turns by being longer, typically and no set orientation. 7. Unfolding of a protein requires breaking the forces within it that stabilize tertiary structure. 8. Mercaptoethanol (breaks disulfide bonds), dithiothreitol (breaks disulfide bonds), detergent (breaks hydrophobic interactions), heat (breaks hydrogen bonds), urea (breaks hydrogen bonds), pH (breaks ionic bonds), or chelators (breaks metallic bonds). 9. Disulfide bonds are important structural components of proteins. 10. The enzyme RNase is interesting in being very stable to heat and other things that denature/inactivate other proteins. RNase has disulfide bonds that help it to remain resistant to denaturation. Heating it to 100 Celsius, which denatures most proteins does not denature RNase. Breaking the disulfide bonds of RNAse with a reagent like...