Chapter 7- Protein Tertiary and Quaternary Structure Flashcards
What is primary protein structure?
the amino acids linked by peptide bonds
What determines how the amino acid folds, its structure and function?
The amino acid sequence and side chains
What are the interactions that determine protein shape?
H-bonds and hydrophobic pockets
What are the 4 types of bonds found in tertiary and Quaternanry structures?
- disulfide bridges (strongest)
- salt bridges
- hydrogen bonding
- hydrophobic interaction (weakest)
What happens when the 4 types of bonds are altered?
it will affect the structure of the protein, and the function, and denature it.
What is the secondary structure of a protein?
Arrangement of the polypeptide backbone of the protein in space. a-helix &beta sheets (due to H bonds between backbone atoms)
What is the protein tertiary structure?
What does it depend on?
the overall 3D shape that results from the folding of a protein.
attractions of amino acid side chains that are far apart along the same back bone.
Which 2 bonds govern tertiary structure?
disulfide covalent bonds and non covalent interactions
what do you call the shape that the protein exists in naturally/?
native state
What is quaternary protein structure?
the way 2+ polypeptide submits associate to from a singe 3D protein unit.
which forces are responsible for quaternary structure ?
non covalent
define protein denaturation
the loss of secondary, tertiary or quartenary protein structure due to disrupting the non-covalent bonds but the peptide bonds and amino acid sequence is still intact
in protein denaturation which structure denatures first?
quart, tert, sec
What agents cause denaturation ?
heat- weak side chain attractions are broken easily
mechanical agitation- eg (forming of egg during beating)
detergent- low concentrations of detergents= denaturation by disrupting the hydrophobic she chains
organic compounds- polar compounds such as acetone/ethanol can interfere with hydrogen bonding by competing for bonding sites
pH change-excess H+ or OH- ions reacts with the basic or acidic side chains in amino acid residues and disrupts salt bridges.
Inorganic salts- sufficiently high concentrations of ions can disrupts salt bridges
how does an unfolded protein adopt native state?
it is described in the genetic code, you can predict 3D structure from primary sequence- all the insturctions are there
