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39 Cards in this Set
- Front
- Back
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phenylalanine is degraded to ___ by ____
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tyrosine by phenylalanine hydroxylase and needs tetrahydrobiopterin
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PKU results from a complete definciency of ___
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phenylalanine hydroxylase
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how to tx PKU
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diet low in phenylalanine and supplemented with tyrosine
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this gives a dark pigment found in urine and cartilage
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alkaptonuria - deficiency of homogentisate oxygenase
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what are the branched chain amino acids
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leucine, isoleucine and valine (degraded by muscle)
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what is defect in maple syrup urine dz
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defective branched-chain alpha-keto acid dehydrogenase
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steps of cysteine synthesization
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homocysteine + serine --> cystathionine (cystathianine synthase) --> cleaved to cysteine and alpha-ketobutyrate (cystathionine lyase) ----- both req PLP
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deficiency of cystathionine synthase
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homocysteinuria
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def of cystathionine lyase
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cystathioninuria
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common genetic dz ; defective rabsorptive transport of cystine and several others - COAL (cystine, ornithin, arginine, lysine) - cystine forms cystine stones
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cystinuria
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intestinal and renal transport protein defect --> tryptophan and leucine transport problems --> pellagra like symptoms (niacin def) -->
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hartnup dz
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important amino acid derivs
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porphyrins, purine and pyrimidines
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type III pryphyrins are
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normal type
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type I porphyrins are
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small part of total porphyrins but in certain dz's --> accumulate and are toxic (cong erythropoeietic porphyria)
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porphyrinogens are
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precursors to prophyrins (colorless)
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what are major sites of heme biosynthesis
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liver and bone marrow
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which enzymes are inhibited by lead
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ala dehydrogenase and ferrochelatase
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which enzyme is inhibited by heme
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ala synthase
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porphyrias ar
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genetic disorders of prophyrin synthesis
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symptoms: cutaneous sensitivity to light --> skin damage, rash, scarring
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cong erythropoetitic porphyrira
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symptoms: abd pain and psych symptoms
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acute intermittent porphyria
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prec factors; ethanol intake, high hepatic iron levels, estrogen, hepatitis and viral infections
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porphyria cunea tarda (also skin blistering and reddish urine)
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deficiency in porphyria cunea tarda
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hepatic urophorphyrinogen decarboxylase
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direct bilirubin represents
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diglucuronide form of bilirubin
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indirect bilibrubin representes
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FREE BILIRUBIN
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conditions that increase indirect bilirubin
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hemolysis, crigler-najjar, gilbert syndromes, low levels of conjugate enzymes in newborns (deficiency of bilirubin glucuronyl-transferase), hepatic damage
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conditions that increase direct bilirubin
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intact bilirubin-conjugation in liver ; may have biliary obstruction (clay-colored stools)-- hepatic damage, dubin-johnson, rotor syndrome
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why is PRPP important
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used in pyrimidine synthesis and purine salvage rxns
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what is first step of de novo biosynthesis of purine nucleotides
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IMP (inosine-5'-monophosphate)
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regulation of purine synthesis
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first 2 steps are feedback inhibited by final products AMP and GMP AND PRPP stim's purine syntheiss
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what does adenosine deaminase do
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deaminates adenosine to inosine (important bc a deficiency --> SCID)
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what is final breakdown produce of purine degradation
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uric acid --> urine
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xanthine oxidase is important why
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bc it catalyzes two rxns hypoxan --> xanth and xant --> uric acid
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adenosine deaminase deficiency
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build up for adenosine --> SCID --> adbnormalities in T and B cells
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lesch-nyhan syndrome
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deficiency of HGPRT --> 2nd'ary gout
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gout
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hyperuricemia (incr production of urate, decr excretion of uric acid or both
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tx for gout
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allpurinol (xanthine oxidase inhibitor)
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orotic aciduria is a def of ___ ; tx is ____
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UMP synthase ; tx = oral uridine
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what does methotrexate do
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inhibit dihydrofolate reductase
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