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86 Cards in this Set
- Front
- Back
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essential fructosuria
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lack of fructokinase – benign asymptomatic – fructose accumulates in urine
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hereditary fructose intolerace (HFI)
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absence of aldolase B leads to fructose-1-p buildup in cells, severe hypoglycemia, vomiting, jaundice and hemorrage, liver failure, Tx remove fructose/sucrose from diet
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glut5
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fructose to blood stream/tissues
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glut2
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High capacity, glucose, fructose, galactose transport to liver
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fructokinase
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fructose -> to fructose-1-P
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aldolase B
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fructose-1-P to D-glyceraldehyde and DHAP
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DHAP
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dihydroxyacetone phospate
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triose kinase
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phosphorylates D-glyceraldehyde to glyceraldehyde-3-P
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fructose metab. In liver
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bypass rate limiting step of glycolysis (PFK-1) much faster than glucose metab. No insulin regulation
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hexokinase
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Fructose in nonhepatic cells to fructose 6-P -- low affinity for fructose (one twentyith of glucose).
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fructose metab. In nonhepatic cells
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through rate limiting step of glycolysis (PFK-1) only small fraction of fructose metabolized this way
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galactokinase
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galactose -> galactose-1-P
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Non-classic galactosemia
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absence of galactokinase causes galactosuria and galactosemia (blood), and converted to galactitol leads to cataracts
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classic galactosemia
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galactose-1-P uridyltransferase (GALT) accumulation of galactose-1-P, liver damage, mental retardation, cataracts from galactitol, galactosuria and galactosemia.
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aldose reductase
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glucose -> sorbitol
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sorbitol dehydrogenase
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sorbitol -> fructose
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polyol pathway
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glucose/galactose to sorbitol/galactitol responsible for galactosemias and DM, leads to cataracts in lens, neuropathy, and nephropathy
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HMP
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Hexose Monophosphate pathway – generate NADPH and ribose-5-P
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glucose-6-P dehydrogenase (G6PD)
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glucose-6-P to 6-phosphoglucono-delta-lactone
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lactonase
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6-phosphoglucono-delta-lactone to 6-phosphogluconate
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6-phosphogluconate dehydrogenase
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6-phosphogluconate to ribulose-5-P
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phosphopentoseisomerase
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ribulose-5-P to ribose-5-P
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transketolase
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transfer 2C needs thiamine pyrophosphate (TPP) cofactor
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transaldolase
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transfer 3C
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G6PD deficiency
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limits amount of NADPH and thus limited reduced glutathione in RBCs, oxidative stress leads to Heinz bodies (denatured proteins cross-linked to plasmalemma) and eventually hemolysis x-linked mutation from mother to son, 11% of african-american males affected, increased rate in those of mediterranean & middle-eastern descent
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HMP need ribose-5-P
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Non-oxidative rxns: fructose-6-P and glyceraldehyde-3-P from glycolysis used to make ribose-5-P
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HMP need ribose-5-P & NADPH
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Oxidative rxns:glucose-6-P used to make NADPH and ribulose-5-P, Non-oxidative rxns: ribulose-5-P converted to ribose-5-P
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HMP need NADPH
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Oxidative rxns:glucose-6-P used to make NADPH and ribulose-5-P, Non-oxidative rxns: ribulose-5-P used to make fructose-6-P and glyceraldehyde-3-P which are fed back into gluconeogenesis to recreate glucose-6-P.
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HMP need NADPH & ATP
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Oxidative rxns:glucose-6-P used to make NADPH and ribulose-5-P, Non-oxidative rxns: ribulose-5-P used to make fructose-6-P and glyceraldehyde-3-P which are used in glycolysis to generate ATP
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glucathione reductase
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uses NADPH to reduces GS-SG (oxidized glutathione) to GS-H (reduced glutathione)
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Heinz bodies
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dark/red blobs on RBC membrane
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amphibolic pathway
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Participates in both anabolism and catabolism
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catabolism
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break down (kata is greek for down, ballein gr. to throw)
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anabolism
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build up (ana is greek for up, ballein gr. to throw)
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TCA cycle
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8 rxns, Third of three stages of catabolism (1st is breaking up macro molecules, 2nd is conversion to Acetyl Coenzyme A (AcCoA)) amphipathic, source of precursors for heme, glutamate, f.a. Cholesterol, ketone bodies, a.a. And glucose
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TCA yield
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one GTP 3NADH 1 FADH_2
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NAD+ and FAD
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coenzymes accepts electrons (is reduced) later re-oxidized by ETC
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NADPH
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used in anabolic reductive biosynthesis
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NADH and FADH_2
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generated in catabolic pathways (3ATP for NADH, 2 ATP for FADH_2)
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NAD+
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Accepts 2 electrons, is difusable
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NAD
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synthesized from vitB3 (niacin)
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niacin (vitB3) deficiency
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pellagra, photosensitive dermatitis, diarrhea and dementa
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FADH+
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accepts 2 electrons, prosthetic group that is permanently attached to enzymes
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FAD
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synthesized from vitB2 (riboflavin)
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riboflavin (vitB2) deficiency
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ariboflavinosis, angular stomatitis aka cheleiosis(cracking at the corners of the mouth), cataracts, glossitis
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pyruvate dehydrogenase (PDH)
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pyruvate to acetyl CoA + CO_2 + NADH– multi-subunit enzyme (occurs in matrix, part of stage II)
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PDH subunits
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E1-E3
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PDH cofactors
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lipoic acid, thiamin pyrophosphate( TPP), FAD, NAD+ and CoA
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PDH regulatory subunits
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PDH phosphatase and PDH kinase
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PDH mutation
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severity related to residual PDH activity, results in lactic acidosis, and neurological sympt. treated with thiamine (vitB1), ketogenic diet, mm relaxants and anticonvulsants
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TPP
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thiamin pyrophosphate (thiamine deficiency results in reduced PDH activity – EtOHism, liver disease, systemic disease, symp:fatigue, irritability, poor memory, anorexia, chest pain, chronic: leads to Wernicke's encephalopathy, Krosakoff syn, or both.
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Wernicke's encephalopathy
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ataxia(uncoordinated mm movements), confusion, eye paralysis)
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Krosakof synd.
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learning and memory deficits
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PDH inhibition
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AcCoA and NADH (products) allosterically inhibit PDH, PDH kinase phosphorylates (inactivates)
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PDH phosphatase
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Insulin signalling activates, or Ca2+ allosterically activates. PDH phosphatase dephosphorylates PDH (activates).
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PDH kinase
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AcCoA, NADH, ATP activate PDH kinase, which phosphorylates PDH (deactivates), ADP, pyruvate and Ca2+ allosterically inhibit PDH kinase
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CTA cycle
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Citric acid cycle, citrate being a Tri-Carboxylic acid, or krebs cycle
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CTA cycle enzyme deficiencies
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lead to lactic acidosis and neuro disfunction (similar to PDH def.)
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citrate synthase
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AcCoA joined with oxaloacetate (4C) to form citrate (6C) – allosterically inhibited by high ATP, inhibited by NADH, SuccinylCoA, acyl CoA derivatives of fatty acids
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anconitase
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citrate isomerized to isocitrate – inhibited by fluorocitrate
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isocitrate dehydrogenase
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(irreversible decarboxilation) isocitrate to alpha-ketoglutarate (5C) + CO_2 + 1 NADH allosteric activated by high ADP level, inhibited by ATP & NADH
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Alpha-ketoglutarate dehydrogenase
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Alpha-ketoglutarate to succinyl-CoA (4C) + CO_2 + 1 NADH – allosterically inhibited by high ATP, also inhibited by GTP, NADH and succinyl CoA – needs lipoic acid, thiamin pyrophosphate(TPP), FAD, NAD+ and CoA
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Succinyl-CoA thiokinase
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Succinyl-CoA to succinate + 1 GTP
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succinate dehydrogenase
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succinate to fumarate + 1 FADH_2
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fumarase
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fumarate to L-malate
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malate dehydrogenase
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L-malate to oxaloacetate + 1 NADH
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pyruvate carboxylase
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pyruvate to oxaloacetate (deficiencies lead to lactic acidosis and neurological disfunction (similar to PDH def.)
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chemiosmotic hypothesis
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H+ gradient (pH and electrical) created during electron flow, is then used by ATPsynthase to make ATP
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NADH dehydrogenase (CMP I)
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pumps H+ to inner memb. Space, accepts e- from NADH
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succinate dehydrogenase (CMP II)
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accepts e- from FADH_2
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ubiquinone-cytochrome c reductase (CMP III)
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pumps H+ to inter memb. Space
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cytochrome oxidase (CMP IV)
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pumps H+ to inter memb. space catalyzes O_2 to H_2O
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ATP synthase (CMP V)
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make ATP using energy stored in H+ gradient ( high H+ conc. In inter memb. Space)
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Coenzyme Q (ubiquinone)
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not a protein, small diffusible – shuttle electrons from 1 or 2 to 3
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cytochrome C
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Small diffusible - transfer electrons from 3 to 4
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std. Reduction potentials (E_0)
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describes tendency to gain/loose electrons (NADH -0.32V easily loose e-) (1/2 O_2/H_2O +0.82V easily gains e-)
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glucose oxidation energy yield
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36-38ATP varies depending on shuttle used for glycolitic NADH transport into mitochondria.
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DNP (dinitrophenol)
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uncouples ETC -change inner memb. Permeability to H+ (leak) → Heat
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UCP1 (in brown adipocytes)
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uncouples ETC -change inner memb. Permeability to H+ (leak) → Heat
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aspirin
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partially uncouples ETC -change inner memb. Permeability to H+ (leak) → Heat
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oligomycin
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specific inhibitor of ATP synthase
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ETC uncouplers
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Fever – hyperthermia
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LHON Leber's Hereditary Optic Neuropathy
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OxPhos disease due to mutation in mitochondiral DNA for NADH dehydrogenase -> nystagmus & progressive blindness (degeneration of CN2)
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MELAS Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes
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OsPhos disease due to mutation in mitochondiral DNA for leucine tRNA -> progressive neurogenerative disease + stroke-like-episodes
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MERRF Myoclonic Epilepsy and Ragged-Red Fiber
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OxPhos disease due to mutation in mitochondiral DNA for lysine tRNA -> myoclonic epilepsy, slowly progressive dementia
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Leigh syndrome
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OxPhos disease due to mutation in mitochondiral DNA for ATP synthase -> nystagmus, optic atrophy, respiratory abn. Hypotonia and spasticity or PDH mutation
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