Protein Structure, Ligand Binding and Conformational Change 1.2 Flashcards
what does amino acid sequence determine?
protein structure
what do allosteric proteins with multiple subunits show?
co-operativity
what is co-operativity?
where changes in binding at one subunit alters the affinity of the remaining subunits
what do modulators do?
they regulate the activity of the enzyme when they bind to the allosteric site
give an example of co-operativity
the binding and release of oxygen in haemoglobin
what factors lower the affinity of haemoglobin for oxygen?
decreased pH and increased temperature
what can the addition/removal of phosphate cause?
it can cause reversible conformational change in proteins
what do protein kinases do?
they catalyse the transfer of a phosphate group to other proteins
where is the terminal of ATP transferred?
to specific R groups
what do protein phosphates do?
they catalyse the reverse reaction
what does phosphorylation do and what does it affect
it brings about conformational change
- affects a proteins activity
give two examples of cellular proteins that are regulated through reversible binding of phosphate
enzymes and receptors
what happens to proteins that are not activated by phosphorylation
others are inhibited
where do allosteric interactions occur
between spatially distinct sites
what do many allosteric proteins consist of?
multiple subunits (have quaternary structure)
describe quaternary structure
exists in proteins with two or more connected polypeptide subunits
what is a prosthetic group?
a non-protein unit tightly bound to a protein and necessary for its function
what can interactions of R groups be influenced by?
temperature and pH
what do binding sites have towards ligands
complementary shape and chemistry
what is a ligand?
a substance that can bind to a protein
what do R groups that are not involved in protein folding allow?
binding to ligands
what happens as a ligand binds to a protein binding site?
conformation of the protein changes
describe the secondary structure
hydrogen bonding along the backbone of the protein strand results in regions of secondary structure.
examples: alpha helices, anti-parallel/parallel, beta-pleated sheets or turns
what is the primary structure?
a sequence in which amino acids are synthesised into the polypeptide
how do R groups vary?
-size
-shape
-charge
-hydrogen
-capacity
-chemical reactivity
how are amino acids classified?
according to they R groups
give examples of R groups
basic (positively charged)
- contains an amino acid side chain (-NH2)
acidic (negatively charged)
- contains carboxylic acid side chain (-COOH)
polar
- carbonyl (-CO), hydroxyl (-OH), amine (-NH2)
hydrophobic
- hydrocarbon group (-CH3)
why can a wide range of functions be carried out by proteins?
because of the diversity of R groups
describe the structure of amino acids
they have the same basic structure, differing only in the R group present
name the two functional groups that amino acids contain
- amine (-NH2)
- carboxylic acid (-COOH)
what is a peptide bond?
a strong covalent bond between a carbon atom of one amino acid and a nitrogen atom of another
what are amino acids linked by and what do they form?
they are linked by peptide bonds and they form polypeptides
describe tertiary structure
the polypeptide folds into a tertiary structure - this change is stabilised by interactions between R groups:
-hydrophobic interactions
-ionic bonds
-LDFs
-disulfide bridges
-hydrogen bonds
what happens due to the binding of a modulator?
conformation of the enzyme changes and alters the affinity of the active site for the substrate
what are proteins polymers of?
amino acid monomers
