Biochem Flashcards
Deficiency in which enzyme causes orotic aciduria, a megaloblastic anemia that cannot be treated with Vit B12 or Folate supplementation, and has no hyperammonemia?
UMP synthase deficiency
Orotic aciduria
Uridine supplementation
What enzyme is inhibited by hydroxyurea?
Ribonucleotide reductase
Pyrimidine synthesis pathway
What enzyme is inhibited by 5-FU?
THymidylate synthase
What enzyme is inhibited by MTX?
Eukaryotic Dihydrofolate reductase
Pyrimidine synthesis pathway
What enzyme is inhibited by TMP?
Prokaryotic Dihydrofolate reductase
Pyrimidine synthesis pathway
What immunologic disorder is caused by adenosine deaminase deficiency?
SCID (AR)
What enzyme is absent in Lesch-Nyhan syndrome? What are the symptoms of this syndrome?
Enzyme: HGPRT def.
Sx:
- Hyperuricemia
- Gout
- Mental retardation
- Self-mutilation
- Choreoathetosis (dysTonia)
What DNA repair enzyme is deficient in Bloom Syndrome?
Helicase
What DNA repair enzyme is deficient in Xeroderma Pigmentosa?
Nucleotide excision repair
Repairs bulky helix-distorting lesions (pyrimidine dimers)
Which DNA repair enzyme is deficient in HNPCC?
Mismatch repair
Which DNA repair process is deficient in Ataxia Telangectasia?
Non-homologous end jointing
Menkes disease causes a defect in which part of collagen synthesis?
Crosslinkage of lysine and hydroxylysine to form collagen fibrils.
Cu is deficient, but it is necessary for crosslinking (lysyl oxidase)
What is the action and function of fomepizole?
- Action
- Inhibits alcohol dehydrogenase
- Function
- Prevent Methanol and ethylene glycol toxicity
Which enzyme is inhibited by disulfiram?
Acetaldehyde dehydrogenase
What is the limiting reagent of ethanol metabolism?
NAD+
RLE of glycolysis
Phosphofructokinase-1 (PFK-1)
(+): AMP, 2,6 Bisphosphate
(-): ATP, Citrate (TCA)
RLE Gluconeogenesis
Fructose 1,6 Bisphosphatase
(+) ATP, acetyl-CoA
(-) AMP, Fructose 2,6 bisphosphatase
RLE TCA Cycle
Isocytrate Dehydrogenase
(+) ADP
(-) ATP, NADH
RLE Glycogenesis
Glycogen Synthase
(+) Glucose-6-P, Insulin, Cortisol
(-): Epinephrine, Glucagon
RLE Glycogenolysis
GLycogen phosphorylase
(+): Epinephrine, Glucagon, AMP
(-): Glucose-6-P, Insulin, ATP
RLE: HMP shunt
Glucose-6-P Dehydrogenase (G6PD)
(+): NADP+
(-): NADPH
RLE: De novo pyrimidine Synthesis
Carbamoyl Phosphate Synthetase II
RLE: De novo Purine Synthesis
Glutamine-PRPP amidotransferase
(-): AMP, IMP, GMP
RLE of Urea Cycle
Carbamoyl Phosphate Synthetase I
(+): N-acetylglutamate
RLE: Fatty Acid Synthesis
Acetyl-CoA Carboxylase (ACC)
(+) Insulin, Citrate
(-) Glucagon, Palmitoyl-CoA
RLE: Fatty Acid Oxidation
Carnitine acyltransferase I
(-) Malonyl-CoA
RLE: Ketogenesis
HMG CoA Synthase
RLE: Cholesterol Synthesis
HMG-CoA Reductase
(+): Insulin, Thyroxine
(-): Glucagon, Cholesterol
