Lecture 6: Understanding Protein Structure Flashcards
Label the peptide bond structure.
Who (2) analyzed geometry & dimensions of peptide bonds in crystal structures of simple molecules having one/few peptide bonds?
Linus Pauling & Robert Corey
__-__ peptide bond length is 10% shorter than in __-__ in most amines and has some ______ bond character (40%) due to resonance.
C-N peptide bond length is 10% shorter than in C-N in most amines and has some double bond character (40%) due to resonance.
Show resonance in the peptide bond.
Planarity of all peptide bonds are ~ _________.
Label the structure.
Planarity of all peptide bonds are ~ coplanar.
Reduced freedom greatly facilitates? Which is directed by? To?
Each ______ acts as a planar unit.
Less rotational felxibility around __-__.
Reduced freedom greatly facilitates protein folding which is directed by amino acid side-chains to stabilize its final conformation.
Each residue acts as a planar unit.
Less rotational felxibility around C-N.
Label torsion angles of a peptide bond. (3)
Planarity of the peptide bond restricts omega bond to ____° (?)
In rare cases, omega = ___° (?), usually w/ _____.
Planarity of the peptide bond restricts omega bond to 180° (trans)
In rare cases, omega = 0° (cis), usually w/ proline.
Label.
What 3 pairs of atoms are nearly coplanar?
The peptide bond is nearly always in the ______ configuration bc it is more favorable.
2 alpha C’s, O=C, N-H are nearly coplanar?
The peptide bond is nearly always in the ______ configuration bc it is more favorable.
When are alpha carbon are on the opposite sites of C-N peptide bond?
Same side?
Trans
Cis
Steric hindrance bw funcitonal groups attached to alpha C’s are greater in what configuration and why?
Cis due to alpha C’s in close proximities
