411: Exam 1 Flashcards
hexokinase activators and inhibitors
activators: insulin, AMP
inhibitors: G6P, ATP
phosphofructokinase activators and inhibitors
activators: AMP, ADP, G6P, F2,6BP
inhibitors: citrate, ATP
enolase inhibitor
fluorophosphates (FPO32-)
pyruvate kinase inhibitors and activators
inhibitors: alanine, citrate, acetyl coA, ATP, cAMP-dependent phosphorylation
activators: F1,6BP, AMP
what sugars do hexokinase and glucokinase break down?
hexokinase: glucose, fructose, mannose
glucokinase: glucose only
difference in capacity and Km between hexokinase and glucokinase
hexokinase: low capacity (slow chem step) and low Km (efficient binding to phosphorylate glucose)
glucokinase: high capacity (fast chem), high Km (different regulatory mechanism
isozymes
- catalyze same rxn but are tissue specific
- allows for different form of regulations
ask emma about this
similarities between hexokinase and glucokinase
- both make G6P
- prevent ATP from reacting with water by causing conformational change once glucose binds (otherwise water will hydrolyze ATP)
what does a reversible reaction say about energy?
low free energy in reaction
what does phosphoglucoisomerase do?
- primes C3 and C4 for later aldolytic cleavage
- mechanism: acid-catalyzed ring opening and base-catalyzed ring closinig
- cis-endeiolate intermediate
what does fructose-2-6-biphosphate do?
increases the affinity of phosphofructokinase for F6P
Class 1 aldolase
- found in animals
- formation of a covalent Schiff Base E-S intermediate
triose phosphate isomerase
- enediol intermediate
- acid/base catalysis
- Glu: base His: acid
- near perfect enzyme Kcat/Km (R-> P)
what does a dehydrogenase enzyme indicate?
electron carrier in the reaction
Glyceraldehyde-3-phosphate dehydrogenase
- gives 2e- as a hydride
- covalent catalysis (covalent bond between E & S)
what kind of mechanism does enolase do?
dehydration reaction
NOT redox
how does NADH transfer electrons?
- H:
- 2e- and a proton
purpose of lactate dehydrogenase
regenerate NAD+ so glycolysis can continue
what happens when lactate gets ionized?
release H+ –> decrease pH –> hemoglobin T state (Bohr effect)
lactate –> lactic acid
liver recylces lactic acid to _______
glucose
slow-twitch vs fast twist muscles
slow: aerobic conditions (endurance,
fast: anaerobic conditions
what is biotin?
a carbon carrier used by pyruvate carboxylase
why does cell add CO2 with pyruvate carboxylase and then take it back off with PEPCK?
decarboxylation drives the formation of the enol that GTP phosphorylates
what does glucagon signal?
low blood glucose (want GNG on)
