Protein Structure Flashcards
What is the general structure of an amino acid?
A central carbon has an amino group, carboxyl group, a hydrogen atom and an R group covalently bonded to it
In what state are amino acids usually present as?
Zwitter Ions
What is an amino acid residue?
What remains of an amino acid after it has been joined by a peptide bond to form a protein
If an amino acid has a high PKA value what does that indicate?
It is a basic amino acid
What is pKa?
pKa tells you the strength of an acid, so how likely the groups are to lose or gain protons
If the pH is less than then pKa value what will happen to the side group?
The group is more likely to be protonated
What is the primary structure of a protein?
The amino acid sequence of the polypeptide chain
What is the secondary structure?
The way the chains fold into conformations like helices etc
What is the tertiary structure?
The overall 3D shape
What is the quaternary structure?
The association between different polypeptides to form a multi-subunit protein
In what type of reaction are peptide bonds formed?
A condensation reaction so a molecule of water is released
What does it mean by saying that peptide bonds are planar?
The atoms all lie in the same plane
Why can’t peptide bonds rotate?
Electrons from the C=O bond of the carboxyl group move between the central carbon and nitrogen from the amino group giving it double bond properties (resonance)
Why do peptide bonds also have trans conformations?
By having the central carbon on opposite sides of the peptide bonds, the R groups will be further apart so won’t repel
Why is the amino acid sequence important?
It determines the physical characteristic and the way in which the protein folds
