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46 Cards in this Set
- Front
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irreversible enzymes in glycolysis (3)
function |
hexokinase/glucokinase (glucose --> glucose-6-phosphate)
phosphofructokinase-1 [PFK-1] (fructose-6-phosphate --> fructose 1,6-bisphosphate)* pyruvate kinase (phosphoenolpyruvate [PEP] --> pyruvate) * rate-limiting step in glycolysis |
|
glucokinase is located in (2)
|
hepatocytes
β-islet cells (gLucokinase) |
|
glucokinase is induced by
|
insulin
|
|
glucokinase:
Km capacity |
high Km (low affinity)
high capacity |
|
hexokinase is inhibited by
|
glucose-6-phosphate
|
|
hexokinase:
Km capacity |
low Km (high affinity)
low capacity |
|
rate-limiting enzyme of glycolysis
|
PFK-1
|
|
PFK-1 is directly inhibited by (2)
|
ATP
citrate |
|
PFK-1 is directly activated by
|
AMP
|
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PFK-1 is indirectly stimulated by
|
insulin
(stimulation of PFK-2 results in fructose 2,6-bisphosphate synthesis) *fructose 2,6-bisphosphate is the most potent activator of PFK-1* (overrides inhibition of PFK-1 by ATP and citrate) |
|
PFK-1 is indirectly inhibited by
|
glucagon
(inhibition of PFK-2 results in inhibition of fructose 2,6-bisphosphate synthesis) |
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2,3 BPG is synthesized during
|
glycolysis (from 1,3 BPG via mutase)
|
|
pyruvate kinase:
activated by inhibited by (2) |
fructose 1,6-bisphosphate
ATP alanine |
|
function of lactate dehydrogenase (LDH)
|
reduces pyruvate to lactate (NAD+ is regenerated)
|
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consequence of reduction of pyruvate to lactate by LDH
|
oxidation of NADH to NAD+
(NAD+ is used in glycolysis by G3P dehydrogenase) |
|
DHAP from glycolysis is used to synthesize
|
TG's
|
|
high-energy intermediates in glycolysis that are used to generate ATP (2)
|
1,3 BPG
PEP |
|
pyruvate dehydrogenase is inhibited (3)
|
NADH
ATP acetyl-CoA |
|
glycolytic enzyme deficiencies result in (2)
|
hemolytic anemia (without heinz bodies; e.g., pyruvate kinase deficiency)
increased 2,3 BPG (O2 unloaded from Hb more readily) |
|
most common glycolytic enzyme deficiency
|
pyruvate kinase
|
|
galactokinase deficiency results in
consequence |
mild galactosemia
galactose is converted to galactitol by aldose reductase in the lens |
|
trapping of galactitol in the lens causes (2)
|
swelling of lens
cataracts |
|
enzyme deficiency:
catracts early in life vomiting and diarrhea following lactose ingestion lethargy liver damage --> hyperbilirubinemia mental retardation |
galactose 1-P uridyltransferase deficiency
("severe galactosemia") |
|
fructokinase deficiency results in
|
essential fructosuria-benign condition
(non-glucose sugar detected by urine dipstick test) |
|
enzyme deficiency:
vomiting lethargy liver damage --> hyperbilirubinemia hypoglycemia (↓ P --> ↓ glycogenolysis and ↓ gluconeogenesis) hyperuricemia renal proximal tubule defect (Fanconi) |
aldolase B (fructose 1-P aldolase) deficiency
("fructose intolerance") |
|
pyruvate dehydrogenase (PDH) complex cofactors
|
thiamine pyrophosphate (TPP) -thiamine (vit. B1)
FAD - riboflavin (vit. B2) NAD+ - niacin (vit. B3) CoA - pantothenate (vit. B5) lipoic acid (the first four water-soluble vitamins + lipoic acid) |
|
PDH:
function activated by (3) inhibited by (3) |
pyruvate --> acetyl-CoA
↑ NAD+/NADH ratio ADP Ca2+ NADH ATP acetyl-CoA |
|
lipoic acid is inhibited by
|
arsenic
|
|
signs of arsenic poisoning (3)
|
vomiting
rice water stools garlic breath |
|
PDH deficiency is common in
reason |
alcoholics
(thiamine deficiency-no TPP) |
|
PDH deficiency results in
|
lactic acidosis
(pyruvate builds up and is converted to lactate by lactate dehydrogenase) |
|
Tx for PDH deficiency
|
increase intake of ketogenic nutrients
|
|
ketogenic nutrients (3)
|
fats
lysine (purely ketogenic aa) leucine (purely ketogenic aa) |
|
pyruvate is converted to alanine by
|
ALT
|
|
anaerobic glycolysis is the major energy-producing pathway in (6)
|
RBC's
leukocytes kidney medulla (very low O2) cornea lens testes |
|
rate-limiting enzyme of the TCA cycle
function |
isocitrate dehydrogenase (IDH)
isocitrate-->alpha-ketoglutarate |
|
isocitrate dehydrogenase:
activated by inhibited by (2) |
ADP
NADH ATP |
|
α-ketoglutarate dehydrogenase complex cofactors
|
thiaminepyrophosphate (TPP) - thiamine (vit. B1)
FAD - riboflavin (vit. B2) NAD+ - niacin (vit. B3) CoA - pantothenate (vit. B5) lipoic acid (the first four water-soluble vitamins + lipoic acid) |
|
α-ketoglutarate dehydrogenase is inhibited by (3)
|
succinyl-CoA
NADH ATP |
|
only enzyme of the TCA cycle not found in the mitochondrial matrix
location |
succinate dehydrogenase
inner mitochondrial membrane (complex II) |
|
NADH dehydrogenase complex I blocked by (2)
|
barbiturates
rotenone |
|
coenzyme Q (ubiquinone) blocked by
|
doxorubicin
|
|
cytochrome b/c1 (complex III) blocked by
|
antimycin A
|
|
cytochrome a/a3 (Cu2+), complex IV, and cytochrome oxidase blocked by (3)
|
cyanide
CO azide |
|
ATP synthase blocked by
|
oligomycin
|
|
uncoupling agents (4)
result in (3) |
uncoupling protein (UCP)
thermogenin (brown adipose tissue) 2,4-DNP aspirin ↓ ATP production ↑ O2 consumption ↑ oxidation of NADH |