Proteins Flashcards
(32 cards)
How is the R group positioned in an α helix protein structure?
Facing the outside where it can interact with the environment
What are the four levels of protein structure?
Primary, secondary, tertiary, and quaternary
What is primary protein structure?
Sequence of amino acids in a polypeptide chain
What determines a protein’s sequence of amino acids?
DNA
How can a change in DNA affect the protein?
It could change the protein structure or function by altering the amino acid sequence
What is a common disease caused by a primary protein mutation?
Sickle cell anemia
What causes sickle cell anemia?
An amino acid mutation in hemoglobin (glutamic acid –> valine)
The 6th amino acid on the beta chain
What is sickle cell anemia?
Hemoglobin molecules assemble as long fibers which causes red blood cells to have a crescent shape
What is secondary protein structure?
Proteins with local folds within their structure
Describe the bonding that creates a secondary protein structure.
Hydrogen bonding between the backbones
R groups aren’t involved!
What are the most common types of secondary protein structures?
α helix and the β pleated sheet
Describe the α helix protein structure.
Secondary structure that looks spiraled
Describe the β pleated sheet protein structure.
Secondary structure that looks folded
What bonds are involved in the α helix and the β pleated sheet protein structures?
Hydrogen bonds connect the carbonyl group to another amino acid’s amino group
What is the bonding pattern in an α helix protein structure?
The hydrogen bond between two amino acids that are 3 apart
ex. carbonyl on amino 1 binds to the amino on amino 5
How many amino acids are in each turn of an α helix protein?
3.6 amino acids
How is the R group positioned in a β pleated sheet protein structure?
They extend above and below the lane
What are the two types of β pleated sheet formations?
Parallel or antiparallel
What is a parallel β pleated sheet?
The N and C terminals of each strand match up (point the same direction)
What is an anti parallel β pleated sheet?
The N and C terminals of each strand don’t match up (point different directions)
What amino acid is an example of a ‘helix breaker’?
Proline
Not compatible in an α helix
What amino acids are commonly found in β pleated sheets?
Amino acids with large aromatic rings
ex. tryptophan, tyrosine, and phenylalanine
What is a tertiary protein structure?
Three-dimensional folding pattern of a protein
Where are the interactions that cause tertiary protein structure?
Between the side chains (R) of amino acids
