Chapter 5- Secondary Structure Flashcards
Primary structure definition
amino acid sequence of protein
Secondary structure definition
local spatial arrangements of the backbone atoms
Tertiary structure definition
3D structure of the entire polypeptide chain
Quaternary structure definition
Spatial arrangements of protein subunits
Peptide bonds are ____ bonds
amide bonds
Proteins result from the formation of covalent peptide bonds by
Condensation
A polymer of two amino acids is called
dipeptide
A polymer of many amino acids
polypeptide
Avg mass of amino acid
110 g/mol
Polypeptides are _____ polymers not branched
linear
The alpha H bonds and carboxyl groups run in the _____ direction
same
Amino acids are always read from the __ terminus to the __ terminus
N (amino terminus), C
In a peptide group a C–N bond is ___ than a simple amine, while a C=O bond is ____ than a simple ketone
Shorter, Longer
Peptide bond has _____ double bond character
~40%
C–N torsion angle is called __ and the C–C torsion angle is called ___
Phi, Psi
The trans configuration is more favored than the cis configuration because
the trans configuration has less steric hindrance and is more stable
the C–N bond is unable to ____
Rotate
Side chains dictate the bond angles because
different bond angles reorient to accommodate other groups around it
An alpha helix can be right-handed or left-handed which means it has
Chirality
Glycine in a peptide chain provides
- flexibility to proteins
- often found in places where proteins make sharp turns
Proline in a protein chain provides
- structure rigidity (due to cyclic side chain)
- may be found in kinks of the protein
polypeptide made of L-alpha amino acids will have n=___ and pitch =____
3.6 amino acids per turn, 5.4 A
____ and _____ of peptide bond point along the long axis (in the opposite direction)
N-H, C=O
The sum of all H bonds contributes to stability which means
more H bonds= more stability
