allosteric regulation of energy metabolism Flashcards
(12 cards)
what is catalysis?
enzyme-substrate binding. e.g. pyruvate kinase binds to PEP and ADP.
what is recognition?
cell surface receptor-signal molecule binding. e.g. insulin binding to insulin receptor.
what is transport?
membrane transport protein-metabolite binding. e.g. glucose transporter.
what are ligands?
when proteins bind to other molecules. can be substrates, hormones, or compounds that regulate protein activity.
how can ligands give proteins their functions?
the specificity of proteins for individual ligands gives proteins many of their functions.
what are the two hypotheses of catalysis?
induced fit model
lock and key hypothesis
what is the induced fit model?
a substrate binds to the active site of the enzyme, which alters it’s shape slightly as the substrate binds. the substrate is split into two products and released from the active site.
what is the lock and key hypothesis?
two separate substrates bind to the active site of an enzyme and attach to create one product.
what is hyperbolic kinetics?
when the rate of enzyme activity increases as the ligand concentration increases until it reaches saturation. most enzymes exhibit hyperbolic kinetics.
what is sigmoidal kinetics?
rate of enzyme activity is modulated by the binding of multiple ligand molecules; and/or other regulatory modulators (effectors). some enzymes exhibit sigmoidal kinetics.
what are the 5 characteristics of proteins showing sigmoidal kinetics?
composed of two or more sub-units.
the sub-units can exist in two different shapes.
when the first [substrate] molecule binds to its binding site on one of the sub-units, it increases the affinity of the second sub-unit for the second [substrate] molecule, so that the second molecule binds more easily to its binding site.
this is described as co-operative binding or co-operativity.
gives rise to the sigmoidal curve.
classic example is haemoglobin binding oxygen.
