Metabolic biochem Flashcards
phosphorylase
adds inorganic phosphate w/out using ATP
mutase
relocates functional group within a molecule
rate determining step of glycolysis
+ and - regulators
phosphofructokinase-1
PFK-1
+: AMP, fructose-2,6-bisphosphate
-: ATP, citrate
rate determining step of gluconeogenesis
+ and - regualtors
Fructose-1,6-bisphosphatase
+: ATP, acetyl-CoA
-: AMP, fructose-2,6-bisphosphate
rate determining step of TCA cycle
+ and - regulators
Isocitrate dehydrogenase
+: ADP
-: ATP, NADH
rate determining step of glycogenesis
+ and - regulators
Glycogen synthase
+: G6P, insulin, cortisol
-: epi, glucagon
rate determining step of glycogenolysis
+ and - regulators
Glycogen phosphorylase
+: epi, glucagon, AMP
-: G6P, insulin, ATP
rate determining step of HMP shunt
+ and - regulators
G6PD
+: NADP+
-: NADPH
rate determining step of de novo pyrimidine synthesis
Carbamoyl phosphate synthetase II
rate determining step of de novo purine synthesis
+ and - regulators
glutamine-phosphoribosylpyrophosphate (PRPP) synthetase
-: AMP, IMP,. GMP
rate determining step of urea cycle
+ and - regulators
Carbamoyl phosphate synthetase I
+: N-acetylglutamate
rate determining step of FA synthesis
+ and - regulators
Acetyl-CoA Carboxylase (ACC)
+: insulin, citrate
-: glucagon, palmiotoyl-CoA
rate determining step of FA oxidation
+ and - regulators
Carnitine acyltransferase I
-: malonyl-CoA
rate determining step of ketogenesis
HMA-Coa synthase
rate determining step of cholesterol synthesis
+ and - regulators
HMA-CoA reductase
+: insulin, thyroxine
-: glucagon, cholesterol
connection between urea cycle and TCA cycle
fumarate, a byproduct in the urea cycle can enter TCA to become malate before OAA
connection between glycolysis, TCA, and Fa synthesis
acetyl-CoA
NADPH
- product of what pathway
- used for what?
- ROS?
- HMP shunt
- used in anabolic processes, respiratory burst, cyt p450 system, glutathione reductase
- creation and neutralization of ROS
Glucokinase
- where is it found?
- insulin effect
- G6P effect
- liver and beta cells of pancreas
- insulin induces it
- no feedback inhibition from G6P
Hexokinase
- where is it found?
- insulin effect
- G6P effect
- most tissues, but not liver or beta cells of pancreas
- insulin doesn’t affect it
- negative inhibition from G6P
gene mutation a/w maturity onset diabetes of the young (MODY)
Glucokinase
glycolysis yields #ATP # NADH
2 ATP
2 NADH
what step in glycolysis gives NADH
G3P or DAG –> 1,3-BPG
pyruvate dehydrogenase reaction
pyruvate + NAD + CoA –> acetyl-CoA + CO2 + NADH
what enzymes does the pyruvate dehydrogenase complex contain (3) and what cofactors do they need
what is it activated by
- pyruvate dehydrogenase (thiamine pyrophosphate (TPP)
- dihydrolipoyl transacetylase (lipoate and CoA)
- dihydrolipoyl dehydrogenase (FAD and NAD)
increased NAD/NADH; ADP; and Ca
what does FAD need?
B2
What does NAD need?
B3
what does CoA need
B5
pyruvate dehydrogenase complex deficiency
- leads to?
- findings?
- tx?
- buildup of pyruvate that is shunted to lactate and alanine (LDH and ALT)
- neuro defects, lactic acidosis, increased serum alanine in infancy
- increase intake of ketogenic nutrients (high fat content or high lysine and leucine content)
what are the only purely ketogenic aa’s?
lysine and leucine
Alanine aminotransferase (ALT)
- needs what?
- what does it do
- b6 (pyridoxine)
- pyruvate to Alanine carries amino groups to liver from muscle
pyruvate carboxylase
- needs what
- what does it do
- b7 (biotin)
- pyruvate to OAA that can replenish TCA or be used in gluconeogenesis
pyruvate dehydrogenase
- needs what
- what does it do
- b1, 2, 3, 5, lipoic acid
- transition from glycolysis to TCA
LDH
- needs what
- what does it do
- b3 (niacin)
- end of anaerobic glycolysis (used in RBCs, leukocytes, renal medulla, lens, testes, cornea)
NADH makes how many ATP in ETC
what ETC structure?
2.5
complex I
FADH2 makes how many ATP in ETC
what ETC structure?
1.5
complex II (succinate dehydrogenase)
direct ETC inhibitors
-mechanism
rotenon (complex I)
cyanide (complex IV)
antimycin A (complex III)
CO (complex IV)
blocks complexes and prevents production of proton gradient
ATP synthase inhibitors
oligomycin
Uncoupling agents
- what does that mean
- ex
- lets H leak across inner mito MB, so weaker proton gradient … produces heat
- 2,4-dinitrophenol, aspirin overdose –> causes fever
irreversible enzymes of gluconeogenesis (4)
- whats the rxn
- what do they need
- pyruvate carboxylase: pyr to OAA (bitoin, ATP, acetyl-CoA)
- PEP caryboxykinase: OAA to PEP (GTP)
- F1,6BPase: F1,6BP to F6P (citrate)
- G6Pase (in the ER): G6P to glucose
HMP shunt
- provides what? (2)
- ATP?
- NADPH for redox rxns
- ribose for nucleotide synthesis
- ATP neither used nor produced
Two phases of HMP shunt
oxidative: irreversible; rate-limiting step w/G6P dehydrogenase
non oxidative: reversible, w/pPEP isomerase and transketolases to make Ribulose 5-P from Ribose 5P
respiratory burst
- what does it involve?
- what cells?
- substrate?
- immune response rapid release of ROS
- NADH oxidase complexes in neutrophils and monocytes
- O2
myeloperoxidase
- what color?
- what is it
blue-green heme-containing pigment
gives sputum its color
enzymes of respiratory burst
- NADPH oxidase (O2 to superoxide)
- Superoxide dismutase (superoxide to peroxide)
- myeloperoxidase or catalase or diffusion
- Glutathione Peroxidase (uses glutathione to cut peroxide)
- Glutathione reductase (reduces glutathione using NADPH)
- G6PD (reduces NADP+ using G6P)
chronic granulomatous disease
pts with the condition cannot generate ROS, so at greater risk of chronic infections by catalse + organisms that can neutralize ROS
G6PD def and ROS
it’s the end point of ROS, so without it, cannot properly protect from oxidative damage
oxidizing agents that can damage RBCs in G6PD def pts (4)
- fava beans
- sulfonamides
- chemo drugs
- primaquine
heinz bodies
- what are they?
- where are they seen?
- precipitated oxidized Hb
- G6PD def
Bite cells
- what happened?
they’re RBCs that have had chunks taken out in attempt to remove Heinz bodies
Enzymes of fructose metabolism (3)
- where does it occur
- fructokinase: fructose to F-1P
- Aldolase B: F-1P to DHAP or Glyceraldehyde
- Triose kinase: Glyceraldehyde to G-3P
- liver
Essential fructosuria
- inheritance
- what is it
- sxs
- AR
- defect in fructokinase
- basically asymptomatic
Fructose intolerance
- inheritance
- what is it
- sxs
- why?
- AR
- def in aldolase B
- hypoGly, jaundice, cirrhosis, vomiting
- accumulation of F-1P in liver
Enzymes of galactose metabolism (3-4)
- Galactokinase: galactose to Gal-1P
- Uridyltransferase: Gal-1P to Glu-1P
- Aldose reductase: galactose to galactitol (the alcohol counterpart)
- 4-Epimerase: involved in the switching of UDP-Gal and UDP-Glu
Galactokinase deficiency
- inheritance
- what enzyme involved
- what happens
- AR
- hereditary def of galactokinase
- accumulation of galactitol, which acts as an osmotic agent so can get inftaile cataracts
Classic galactosemia
- inheritance
- what is what enzyme involved
- what happens
- what can it lead to
- AR
- absence of Gal-1P uridyltransferase
- accumulation of Gal-1P and galactitol in lens and liver
jauntice, MR, cataracts, FTT - can lead to E. Coli sepsis in neonates
Sorbitol
- what is it
- purpose?
- enzymes involved in its metabolism (2)
- glucose’s alcohol counterpart
- traps glucose in cells
- Aldose reductase (glucose to sorbitol using NADPH) + Sorbitol dehydrogenase (sorbitol to fructose using NADP+)
What cells have both enzymes of sorbitol metabolism (3)
- liver
- ovaries
- seminal vesicles
what cells have only the first enzyme of sorbitol metabolism (3)
- schwann cells (so can get peripheral neuropathy)
- Retina (so you can get retinopathies)
- renal cells
types of lactase deficiency (3)
- primary
- secondary
- congenital lactase deficiency