Metabolism Major Enzymes Flashcards
1
Q
Hexokinase
A
- Used in glycolysis(step 1)
- Phosphorylates glucose into glucose-6-phosphate
- Uses ATP
- Traps glucose in cell(GLUT cannot bind G6P)
- G6P can be used in glycolysis to make energy or stored for later(glycogen)
2
Q
Phosphofructokinase(PFK-1)
A
- Used in glycolysis(step 3)
- 2nd ATP requiring step
- Transfers phosphate from ATP to C1 hydroxyl of Fructose-6-phosphate -> makes Fructose 1,6 bisphosphate
- Activated by AMP, ADP, or Fructose 2,6-bisphosphate
- Inhibited by ATP
3
Q
Pyruvate Kinase
A
- Used in glycolysis(step 10)
- Releases ATP
- Uses phosphenolpyruvate(PEP) to form pyruvate
- Inhibited by phosphorylation and other allosteric regulators
- In low glucose levels: glucagon/epinephrine/cortisol uses protein kinase to phosphorylate -> inactive
- In high glucose levels: insulin use phosphatase to dephosphorylate -> active
- Activated by AMP, F1,6BP
- Inhibited by ATP, Alanine, Acetyl-CoA
4
Q
Phosphoglucomutase
A
- Used in glycogen synthesis
- Glucose still phosphorylated to make G6P -> G6P isomerized to form Glucose-1-phosphate
- In glycogenolysis: converts glucose-1-phosphate back to glucose-6-phosphate
5
Q
UDP-glucose pyrophosphorylase
A
- Used in glycogen synthesis
- Uses UTP to activate glucose-1-phosphate to make UDP-glucose
6
Q
Glycogen Synthase
A
- Used in glycogen synthesis
- Uses UDP-glucose to create alpha(1,4) glycosidic bonds on non-reducing ends of glycogen
7
Q
Glycogen Phosphorylase
A
- Used in glycogenolysis
- Activated with glucagon and epinephrine signaling
- Uses Pi to release glucose-1-phosphate from non-reducing ends
- Inhibited by ATP and glucose-6-phosphate
- Stimulated by AMP
8
Q
PDC Enzymes
A
- E1: Decarboxylates pyruvate
- E2: Transfers acetyl
- E3: Dehydrogenase to convert FADH to FAD
- Acetyl CoA inhibits E2
- NADH inhibits E3
9
Q
Succinate Dehydrogenase
A
- Used in TCA and ETC
- Forms fumarate from succinate in TCA cycle
- Complex 2 in ETC. Where FADH comes in
10
Q
Regulated enzymes in TCA
A
- Reactions that are favorable(negative delta G)
- Citrate synthase(Step 1): Uses acetyl-coA and oxaloacetate to make citrate. Inhibited by citrate
- Isocitrate dehydrogenase(Step 3): Uses isocitrate to form alpha-ketoglutarate. Inhibited by NADH. Stimulated by ADP and Ca2+. Releases CO2 and NADH
- Alpha-ketoglutarate dehydrogenase(Step 4): Uses alpha-ketoglutarate to form Succinyl-CoA. Releases NADH and CO2. Inhibited by NADH. Stimulated by Ca2+
11
Q
Enzymes used in ETC
A
- NADH-Q Oxidoreductase: Complex 1
- Succinate-Q reductase: Complex 2
- Q-cytochrome c oxidoreductase: Complex 3
- Cytochrome c oxidase: Complex 4
12
Q
ATP Synthase
A
- F1 carries out catalytic synthesis of ATP in matrix
- F0 is integral membrane protein and anchors complex to membrane
- Binding of H causes rotation in ring of c subunits in F0
- Rotation of ring rotates, rotates gamma subunit including a conformational change in the beta subunit. H+ released into the matrix
- Conformational changes in the F1 beta-subunits are responsible for ATP synthesis
13
Q
Triacylglycerol Lipase
A
- Hydrolyze ester bonds to produce free fatty acids and glycerol
- Activated by phosphorylation from PKA
- Also known as hormone-sensitive lipase
14
Q
Acyl CoA Synthetase
A
- Catalyzes reversible reaction using ATP to form fatty acyl CoA
- Pyrophosphate hydrolysis to 2 Pi drives reaction in forward direction
15
Q
Carnitine Shuttle
A
- Used to move acyl-CoA into matrix for beta-oxidation
- Carnitine Acyltransferase 1: Moves acyl chain onto carnitine from CoA
- Carnitine Acyltransferase 2: Moves acyl chain back onto CoA
