Lecture 7/01.29.25 Flashcards
(20 cards)
What is primary structure in proteins?
The order amino acids are linked.
What is the secondary structure in proteins?
The regular folding patterns whether it be a helix, B pleated sheet, or random coil/loop region
What is the tertiary structure
The 3 D dimensional sequence that is folded
What is the quaternary structure?
The final form that is held together
What determines primary structure?
Genetic code. To code for each amino acid, nucleotide triplets and codons are used. This allows for 64 different combinations.
What were the rules according to Pauling?
- bond lengths and angles of a.a and peptides must be fairly consistent with difraction studies
- no two atoms should approach closely than their van der waals radii
- the 6 atoms in the peptide-amid should be coplanar and rotation is possible around adjacent a carbon
- some noncovalent bonding is necessary, usually hydrogen bonding
What are the structures that follow the criteria from Pauling?
Right handed a helix and B sheet. This is because each structure the amide group is planar and all amide protons and carbonyl carbons are involved in H bonding. These are the most common
What is true about the a helix?
They have rod like in structure, inner backbone with R group extending outward, CO and NH are h bonding. The right handed is the most common
How are B sheets made?
from 2 or more B strands
Are B sheets parallel or antiparallel?
both
What is a polypeptide (polyproline) II helix?
A secondary structure that does not satisfy H bond, it is left handed, has many prolines, and maybe glycine.
What is true about secondary structure function?
Proteins can be fibrous, long and extended, and globular.
What is an example of a fibrous protein?
collagen
What is in collagen?
It has hydrogen bonding between amide protons and carbonyl carbons but also hydroxyproline that makes it stronger through its bonding
What happens if there is weak collagen?
Causes scurvy, anemia, atherosclerotic plaques, poor wound healing, muscle degeneration
What is the tertiary structure of proteins?
Where it shows the conformation of the whole polypeptide in 3 dimensions
What stabilizes the tertiary structure?
Non-covalent bonds and sometimes by the covalent disulfide bonds between cysteines.
Tertiary structure determines what?
The function of a globular protein
What is true about globular folding?
It is highly favorable over random coils. It is intricate where side chains are folded inside and hydrophilic towards water
How do antiparallel B strands and sheets affect antiparallel?
It can arise hairpin folding of a single strand
