Biochemistry Lecture 7 - Protein Structure and Function Flashcards
(24 cards)
Proteins fold to maximize _______.
Weak forces (such as hydrogen bonds).
What test is used to identify proteins?
Western blot.
How many amino acids are there?
20
Which amino acid has the smallest R group? What function does this AA often play in proteins?
Glycine, the R group is a hydrogen. It is often found in tight bends in protein structure.
What does herceptin do?
Treats breast cancers.
What amino acids absorb UV light the strongest?
Tryptophan and tyrosine. The ones that have the letters T, R, and Y at the start! TRY to remember that shit.
What is a “molten globule” state?
When the nascent protein’s hydrophobic groups begin to aggregate - and at this point the protein is insoluble because it’s hydrophilic groups have not covered up the hydrophobic ones.
What do chaperone proteins do for regarding synthesis?
They assist protein folding, or they chaperone them to proteases if they get misfolded.
Which amino acid is the “alpha helix breaker?” Why?
Proline, it has a five membered ring and doesn’t fit.
Define amphipathic.
Having both hydrophobic and hydrophilic parts.
What are the two secondary structures of proteins?
Alpha helix and beta sheet.
Contrast side-chain proximity between AA’s in the helix vs. in the sheet.
R groups are relatively close to each other in the helix, whereas in the sheet the side chains are 180 degrees from each other.
In what major organ is elastin found?
Lungs
What part of the CFTR protein binds and hydrolyzes ATP? What does ATP hydrolysis do to the protein?
NBD 1 and 2. ATB binding and hydrolysis changes the conformation, allowing chloride ion to pass through.
What part of the CFTR protein gets phosphorylated? What effect does the phosphorylation have on the protein’s activity?
The Regulatory Domain gets phosphorylated. This activates the CFTR channel.
What is the structure of elastin? What are the links called? What amino acid is responsible for the linking and how many residues are involved?
Elastin forms a flexible network linked via cross-links. The links are formed by four lysine residues and are called desmosine residues.
Where is keratin found?
Hair, nails.
What structure makes up keratin?
Alpha helices, very tightly wound up.
What is the major buffer inside cells?
Phosphate.
What is pKa?
The pH at which the molecule is 50-50 acid-base form.
At what pH is maximal buffering achieved?
pKa
What is meant by the isoelectric point of a protein?
The pH where a protein achieves neutral charge.
What is the major buffering system in the blood?
Bicarbonate.
Why is aspirin most readily absorbed in the gut where the pH is lower?
It’s carboxylic acid group is protonated, resulting in a neutrally charged molecule. Uncharged molecules can pass the PM easier!
