BICH 410 Lecture Notes - Lecture 9: Alpha Helix, Peptide, Hydrophile
Document Summary
There is still a large number of proteins that have unknown functions*** Rigidity of peptide bonds help with the rm structure of molecular compositions - planar arrangement. Can have two possible conformations- cis or trans. Trans conformation is almost always more favored over cis by 8kj mol. *proline is the exception with 10% of the proline residues in proteins following a cis peptide bond because of its cyclic structure and secondary alpha carbon. Proline: limit the range of phi and psi angles due to conformation restriction. Glycine: offer greater number of potential conformations due to less sterical hindrance. Alpha helix amino acids tend to be hydrophilic, polar, and have large r- groups. Parallel structured polypeptides are less stable because of the orientation of the non- linear hydrogen bonds. Beta sheets tend to have smaller, hydrophobic amino acids. B turns and loops = reverse turns or b bends. Proline and glycine are prevalent in b turns.
