Intro to protein biochemistry Flashcards
Function of protein (6)
Transport Catalyse Communication Defence e.g. antibodies Control Structural
Structure of amino acid (draw)
(h3n+) (R) c (coo-)(H)
What happens when proteins in solution + physical pH 7
Assume zwitterion state
What causes a zwitterion
Charged/ ionised + amino and - carboxyl group
Primary structure
Covalent structure of amino acids w/ peptide bonds
Secondary structure characteristics (3)
Alpha helix
Beta pleated sheets
Beta loop regions
What causes the folding in the secondary structure
Hydrogen bonds between peptide bonds cO + nH
Which part of the secondary structure is hydrophobic and which is hydrophilic
Beta loop region = hydrophilic therefore on exterior
Alpha helices + beta sheet folded interior to avoid watery environment
Define hydrophilic
Can interact with water
lone pair of electron on electronegative oxygen interact w/ electropositive H group
Define hydrophobic
Cannot interact w/ water
Polar
Define amphipathic
Regions that are polar + non polar
Characteristics of unfolded protein (3)
Sticky
Prone to aggregation
Prone to degradation
Characteristic of folded 3D protein form
More stable
bc more bonds + more thermostable so need more energy to break
Non covalent bonds in tertiary structure (3)
Hydrogen bonds Van der Waals forces (dipole-dipole interactions) Electrostatic interactions (salt bridges) between charged residues
Covalent bonds in tertiary structure (2)
Peptide Disulphide bridges (s-s)
Where disulphide bridges found + why
Only in secretory pathway, mitochondria, lumenal ER
bc cytoplasm v reducing which will break down bridge
Define native structure
Folded, active form
Define random coil
Unfolded structure w/ no secondary structure
Define conformation
Change in 3D structure through rotation of bonds (no breakage)
Define denaturation
Destruction of native structure by change of conformation
breaks peptide bonds but can return to active conformation
Define degradation
Breaking of covalent bonds to smaller molecules
Aim of protein homeostasis
Ensure correct amount of functional protein at all times
Important in diseases
What ensures protein homeostasis (3)
Production (protein translation)
Folding (controls if protein functional
Trafficking (correct amount functional protein to correct part of cell, where needed)
Degradation
What happens when protein homeostasis goes wrong
Chaos in cell
Stress response
Cell death
