metabolic control via enzyme regulation Flashcards
the rate determining step
determines overall flux through the pathway by acting as a bottle neck
usually the first enzyme
how to identify the RDS
measure the Vmax (lowest = RLS)
compare Keq and mass action ratio MARs
we can test the RDS by using the crossover point this is done by
increasing/decreasing the flux by treating with hormones
crossing over point identifies regulatory speed
in glycolysis, what are the RDS
hexokinase phosphofructokinase enolase Small Vmax MARS is very small compared to Vmax
so to test MARs we have to go in
anaerobic conditions for crossover
muscles dont have oxygen so work faster to produce ATP
control by metabolites,
product inhibition
allosterism
product inhibition
negative feedback, the more you make the more you inhibit
f-2,6-bisp activates
PFK1 and inhibits F-1,6-bisphosphotase
control by phosphorylation
activate g protein- activate adenayl cyclase- activate cAMP- activate PKA
PKA phosphorylates what
Phosophoylase kinase
Phosophoylase kinase phosphorylates what
phosphorylase b - phosphoylase a (increasing glycogenolysis)
insulin causes the inactivation of
GSK 3 by phosphorylation which allows glycogen synthase a to activate
adrenaline, causes PKA to phosphorylate
inhibitor 1
inhibitor 1 P causes the
inhibition of PP1
PP1 inhibition allows PKA to phosphorylate
phosphorylase kinase to active form
which then cause phosphorylase b - phosphorylase a
PKA inhibits PP1 in the action of
glycogen synthase
AMP activated protein kinase
links allosterism and phosphorylation
phosphorylates multiple targets
Control by acetylation eg malate dehydrogenase
attachment of acetyl group to a lysine side chain
catalysed by K acetyltransferase
loss of +ve charge
control by expression
transcriptional factors
control by expression, glucagon
PKA activates (inside nucleus) CREB by phosphorylation
