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31 Cards in this Set

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summary of Heme synthesis
glycine & SCoA
delta aminolevulinate
(from mito into cyto)
porphobilinogen
proprophorinogen III
(then into mito for M, P & V)
protoporphoryn IX
Heme

build porphoryn ring
-linear pyrrole
-cyclize to porphyrinogen
enzymes for heme synthesis
ALA synthase
ALA dehydratase
Uroporphyrinogen I synthase w/Uro III cosynthase
ferrochetolase
summary of heme degredation
heme
biliverdin (via heme oxegynase + O2 & NADPH)
bilirubin (via biliverdin reductase)
bilirubin diglucuronide (via UDP glucuronyl transferase)(conjugated)
Fe2+ protoporphyrin IX
heme
iron state in heme
Fe2+
location of heme synth
all cells
(not recycled-toxic)
no storage

mito then cyto then mito again
rate limiting step of heme synthesis
ALA synthase
in mitochondria

two isoforms:
-E erythroid
-N non-erythroid
regulation of heme synthesis
ALAS-E
-IRE in 5'
-increased Fe gives increased ALAS-e
(like ferritin)

ALAS-N
-negative feedback
-by heme & glucose
-induced by many drugs

insertion into mito is another poit of reg
porphobilinogen synthetase
aka ALA dehydratase
-in cyto
-zinc enzyme
-lead poisoning (b/c displaced)
function of Uro III cosynthase
to prevent spontaneous ring formation
(need AP AP AP PA)

with PBG deaminase
gives coproporphyrinogen III
substrate that returns to mito (in heme synth)
coproporphyrinogen III
(from PGB deaminase & cosynthase)
fate of coproporphyrinogen III
return to mito
oxidized
convert 2 propyl side chains to vinyl
characteristics of protoporphyrin IX
oxidized
fully conjugated ring system
from protoporphyrinogen IX
(colorless)
receives iron to become Fe 2+ protoporphyrin IX
ferrochetolase
adds iron to protoporphyrin IX
types of heme
a, b & c
differ by side chains & linkage to protein (covalent or non)
all have protoporphyrin
causes of porphyrias
no dz assoc ALA synthase mut

any other enzyme
nervous system
skin

variagate= have to stay out of the light
variagate porphyria
have to stay out of the light
mut in PGen IX oxidase

affects NS, skin
heme oxygenase
(catabolism)

in macrophages
opens ring
uses NADPH & O2
gives CO (only rxn in body), Fe3+ & NADP+
gives biliverdin
reaction producing CO
(NOT CO2)
heme oxygenase
degrade heme
open ring
in MPs
releases iron (Fe3+)
glucuronic acid
produced in liver
to conjugate bilirubin
from UDP glucose & 2 NAD
bilirubin UDP glucuronyltransferase
transfer UDP glucuronic acid onto bilirubin

not ready til birth
(premies jaundiced, babies take a while to activate)
bilirubin produced by
reduction of biliverdin
(via reductase)
uses NADPH
2 types hyperbilirubinemia
prehepatic
-excess heme destruction
-excess of conjugated
-Rotor's
-Dubin Johnson

hepatobiliary
-lost ability to conjugate
-Crigler Najjar
-Gilbert's
vanden burg reaction
measures bilirubin
(direct vs indirect)
(prefixes go together)
benign congenital liver disorder
males more than females
teens - early 30s (onset)
Gilbert's
tx w/phenobarb
(stimulates UDP g transferase activity)
severe unconjugated hyperbilirubinemia at birth
Crigler-Najjar
fatal when enzyme absent
(UDP g transferace)
mild conjugated hyperbilirubinemia
Dubin-Johnson or Rotor's
purpose of bilirubin
antioxident
-supress oxidation of lysosomes
-protect myocardium & nervous tissue
phototherapy for jaundice
opens H bonds
increases solubility
heptaglobin
picks up Hgb (if RBC lyses) & transport to liver
hemopexin
picks up loose heme