1.2(c) Protein Structure, Ligand Binding and Conformational Change Flashcards
What do R groups give amino acids
Their unique chemical properties
What are the 4 types of amino acids
Acidic (negatively charged)
Basic (positively charged)
Polar
Hydrophobic
What are acidic aminos acids
Generally, have a -COOH on the R group and are negatively charged. They are strongly hydrophilic
What are basic amino acids
Have an NH3 or NH2 group and are positively charged. They are strongly hydrophilic
What is a polar amino acid
They all have a nitrogen, oxygen or sulphur (NOS). They are hydrophilic as they form weak hydrogen bonds with water molecules
What is a hydrophobic amino acid
The R group does not contain OH, COOH, NH2 or SH, they are carbon heavy. They are hydrophobic and non-polar and often have benzene rings
Name the 4 types of protein structure
Primary
Secondary
Tertiary
Quaternary
What is primary structure
Amino acid sequence that are synthesised into a polypeptide
What is secondary structure
Alpha-helix, beta pleated sheets and turns.
How are turns brought about
Changes in direction are caused by hydrogen bonding along the back bone
Beta pleated sheets can be…
Parallel of Anti-parallel
What is tertiary structure
Refers to the overall folding of the polypeptide and is stabilised by different interactions between R groups e.g., Hydrophobic interactions, ionic bonds and disulphide bridges
What is a prosthetic group
Non-protein parts that give proteins extra function e.g., haem in haemoglobin
What is quaternary structure
2 or more connected polypeptide subunits
What is a ligand
A substance that can bind to a protein
What is conformational change
Ligand binding changes the conformation (structure) of a protein, this causes a functional change in a protein
What is an allosteric enzyme
AN enzyme that can have its activity altered by a ligand called a modulator
What is an allosteric modulator
They regulate the activity of the enzyme when they bind to the allosteric site
How to positive modulators affect enzyme affinity
Increase it
How to negative modulators affect enzyme affinity
Reduce it
What is Co-operativity
The binding of a substrate molecule to one active site of an allosteric enzyme increases the affinity of the other active sites for binding
Give an example of co-operativity
Haemoglobin
Lower pH and higher temperature means
Lower affinity for haemoglobin and so the binding of oxygen is reduced
Higher pH and lower temperature means…
Higher affinity for haemoglobin and so the binding of oxygen is promoted
