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20 Cards in this Set
- Front
- Back
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products of HMP Shunt
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R5P- pentoses for nucleotides
NADPH- reducing power -FA synth (VLDL secretion, TG storage, milkfat synth) -cholesterol synth -cholesterol homeostasis & bile salts -protect against RO dmg -NO synthesis (arginine) -phagocytes |
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methemoglobin
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produced 1-3% of Hgb
generates oxegyn rad metHgb reductase removes oxidizes RBC membranes contains Fe3+ (not 2 like Hgb) |
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diaphorase
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methemoglobin reductase
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acquired methemoglobinemia
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G6P Dh defeciency is cofactor in acquired methemoglobinemia
(heteros protected malaria) from ingested oxidizing agents (naphalene, paraquat, primaquine, fava beans) |
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congenital methemoglobinemia
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deficiency in metHgb reductase (diaphorase)
Met Hgb oxidizes RBC membranes |
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treatment for methemoglobinemia
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(Fe3 back to Fe2)
methylene blue electrons onto MB uses HMP nonenzymatic |
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RBC rxns requiring NADPH
(protective) |
SOD (generates H2O2)
Catalase (gives H20) Glutathione peroxidase (oxidizes reduced glutithione- uses selenium- GSH to GSSH/G- generates NADPH) Glutathione reductase- keeps it reduced (generates NADP) metHgb reductase |
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oxidation of Hgb
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susceptible b/c SH gps (on cysteine)
problem in RBC mixed disulfide formation damages membranes forms Heinz bodies |
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Heinz body
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from mixed disulfide formation
Hgb covalent bond to membrane leads to pitting |
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pitting
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spleen chops part of RBC b/c of mixed disulfide rxn)
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killing reactions of NADPH
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NADPH oxidase
-for oxygen burst -cyto B5 & NADPH -on ER -produce NADP+ & ox rad -CGD SOD -gen H2O2 (isoenzyme of RBC SOD) Fenton Rxn (generate OH rad) -Fe2 Myeloperoxidase (forms bleach) |
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NADPH oxidase
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-for oxygen burst
-cyto B5 & NADPH -on ER -produce NADP+ & ox rad -deficiency gives CGD -test w/NBT |
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SOD
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2 isoenzymes
in RBC causes damage in phagocyte kills bug makes H2O2 (for Fenton rxn) |
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Fenton reaction
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nonenzymatic
uses Fe2+ (oxidizes to 3) generates OH rad (most powerful radical) kills parasite (via hole in membrane) |
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myeloperoxidase
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produces bleach (hypochloris acid)
kills bugs cytochrome enzyme gives pus its color |
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chronic grannulomatous disease
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deficient NADPH oxidase
test w/nitroblue tetrazolium NBT turns blue when reduced (pos sign-enzyme functioning) |
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HMP shunt pathway
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Oxidative:
G6P to R5P (2NADPH) G6P Dh - gives 1 NADPH lactonase 6 P glucanate Dh- gives 1 NADPH & ribublose 5 p isomerase- gives ribose 5P Non-Oxidative transketolase - back to F6P -thru triose, tetrose, heptose |
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transketolase
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non oxidative pathway of HMP
returns ribose 5 P to F6P via trisoe, tetros or heptose thiamine dependent easy to measure (in RBC) good marker for thiamine def |
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protective reactions for NADPH
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glutithione peroxidase
-removes H2O2 -produces reduced GSSH -uses NADP+ (oxidized) -generates H2O & O2 glutithione reductase -regenerates reduced GSH -uses NADPH (reduced) |
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sources of radicals in RBCs
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SOD- H2O2 & O2
(Catalase removes to O2 &H2O) |
