Lecture 5: Protein Structure Flashcards
Secondary Protein Structure
Results in alpha-helix or pleated sheets…
Defined by backbone -H bonding
Primary Protein Structure
The amino acid sequence making up the backbone
Where does rotation occur in an amino acid sequence? Where doesn’t rotation occur?
Occurs- b/w alpha-carbon and carboxyl-carbon and alpha-carbon and nitril group
Doesn’t Occur- b/w carboxyl-carbon and nitril group
What are the two rotational terms and where do they describe rotation
Phi- nitril group and alpha-carbon
Psy- alpha-carbon and carboxyl-carbon
What is the average number of amino acids in an alpha-helix?
12
How many amino acids/turn in an alpha-helix
3.6
How does -H bonding occur in an alpha-helix
It runs parallel to the helix
Which form of secondary structure is most stable?
Alpha-helix
What is a 310-helix
A tighter/more compact alpha-helix where -H bonding occurs between the 3rd atom (the Oxygen of the carbonyl group) and the 10th atom (the Hydrogen of the nitril group)
How many degrees b/w each amino acid in an alpha-helix
100 degrees
Why are beta-strands less stable than alpha-helices
They have -H hanging off the ends that have nothing to bond to and, therefore, make the sheet “sticky”
How long is the average beta-strand? How long is the average beta-sheet?
Beta-strand: 4-5 amino acids
Beta-sheet: 21-22 strands
What is a collagen triple-helix
A rope like strand where left-handed helices wrap around each other (braid together) in a right-handed fashion
What is a coiled-coil helix
A strand where 2 alpha-helices (right-handed) come together in a left-handed fashion
Is an alpha-helix right or left handed?
Right
