Protein Structure & Function Flashcards
What type of reaction creates peptide bonds? And where does it occur?
Condensation reaction between the carboxylic and amino group
Which amino acid is the most HYDROPHOBIC?
Isoleucine
Which amino acid is the most HYDROPHILIC?
Arginine
What does a POSITIVE value indicate on a hydropathy index?
A polypeptide most likely to be found in the membrane
TRUE OR FALSE?
Polypeptide chains are planar?
True
TRUE OR FALSE?
Alpha helices have one positive angle and one negative angle?
False.
They have 2 negative angles
TRUE OR FALSE?
Beta pleated sheets have one positive angle and one negative angle?
True
Which amino acids do Zinc Finger Motifs require?
2x Cysteine
2x Histidine
What amino acids are required for catalytic sites on enzymes?
- Serine
- Asparagine
- Histidine
What interactions contribute to the stabilisation of the protein molecule?
- Hydrophobic Ionic Interactions
- Hydrogen bonding
- Van der Waals forces
What function(s) does Phosphorylation usually modulate?
Regulation
What function(s) does Glycosylation usually modulate?
- Folding
- Stability
- Regulation
What function(s) does Acetylation usually modulate?
Regulation
Which amino acids have a phosphate group added to them during Phosphorylation?
- Serine
- Threonine
- Tyrosine
What function(s) does Hydroxylation usually modulate?
Regulation
What function(s) does Methylation usually modulate?
- Regulation - epigenetics
Which amino acids are involved in Hydroxylation?
- Lysine
- Asparagine
TRUE OR FALSE?
Every AA residue is essential for function?
False.
Every AA contributes towards the final structure, every residue is NOT essential for function
What percentage of human proteins are polymorphic?
20-30%
Where do cells acquire the molecules and ions they need?
Extracellular Fluid (ECF)
What is a Chemical Gradient?
A difference in solute concentrations across a membrane
What is an Electrical Gradient?
A difference in potential/charge across a membrane
What is Resting Potential?
Static membrane potential
What is an Action Potential?
Rapid rise and fall in membrane potential causing similar cells to depolarise
What ions flow in and out of a cell during an Action Potential?
- INWARDS - Na+
- OUTWARDS - K+
What AA sequence is found in the signature motif of K+ channels?
- Threonine
- Valine
- Glycine
- Tyrosine
- Glycine
Which technique was mostly used for Ion Conductance measurements?
Patch Clamping - single channel recordings
What shape is the Bacterial KcsA Channel?
V shaped tetramer
How many residues does the Bacterial Kcs Channel have?
158
How many subunits does the Bacterial Kcs Channel have?
Four identical subunits
What is in the middle of the membrane of the the Bacterial Kcs Channel?
Hydrated K+
What THREE segments make up the subunit structure of the Bacterial Kcs Channel?
- Selectivity Filter
- Cavity / Lake
- Internal Pore
What amino acids make up the Selectivity Filter for K+ channels?
TVGYG
* Four layers of carbonyl atoms (VGYG)
* One layer of hydroxyl atoms (Thr)
How many binding sites does the Selectivity Filter have for dehydrated K+?
4
How many coordination sites do K+ ions have?
8 sites occupied by H20 molecules
Which negatively charged amino acids are at the K+ ion channel entrance?
Glu and Asp
What amino acids are on each voltage sensor of the ion channel?
4 Arg
How does ion channel inactivation occur?
N-terminal ball plugs the pore from the cytoplasmic side
