PORPHYRIN CHEMISTRY AND METABOLISM Flashcards

1
Q

prophyrins are heterocyclic macrocycles composed of four modified pyrrole subunits interconnected at their carbon atoms via ______

A

methyne bridges

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2
Q

strong red fluorescence are due to the _______ joining the pyrrole rings

A

double bounds

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3
Q

porphyrins have the ability to form complexes with _______ bound to ____________ atom of pyrrole rings

A

metal ions
nitrogen

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4
Q

responsible for the green seen in leaves
contains magnesium bound to the nitrogen

A

chlorophyll

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5
Q

_________ and _________ can also be measured in urine by appropriate calorimetric tests

A

ALA and PBG

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6
Q

_______ are a group of diseases caused by abnormalities in the pathway of biosynthesis of the various porphyrins

A

porphyrias

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7
Q

transport of oxygen in blood

A

hemoglobin

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8
Q

storage of oxygen in muscle

A

myoglobin

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9
Q

involvement in electron transport chain

A

cytochrome c

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10
Q

hydroxylation of xenobiotics

A

cytochrome P450

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11
Q

degradation of hydrogen peroxide

A

catalase

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12
Q

oxidation of tryptophan

A

tryptophan pyrrolase

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13
Q

heme is synthesized from ______– and _______

A

succinyl coa and glycine

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14
Q

type III uroporphyrinogen uses the enzyme

A

Uroporphyrinogen III synthase

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15
Q

the conversion of coproporphyrinogen III to protoporphyrinogen III happens in the _________

using the enzyme _______

A

mitochondria

coproporphyrinogen oxidase

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16
Q

the last reaction (8th step) in heme synthesis involves the incorporation of ____________ iron into protoporhyrin III in a reaction catalyzed by _________ (heme synthase)

A

ferrous iron
ferrochelatase

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17
Q

heme synthesis in most mammalian cells with the exception of ________

A

mature erythrocytes

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18
Q

hepatic form of ALA synthase

a regulatory enzyme that catalyzes the rate limiting reaction in the synthesis of heme in liver

A

ALAS1

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19
Q

erythroid form of ALA synthase

A

ALAS 2

20
Q

____________ and ____________ exhibited by some patients with congenital erythropoetic porphyria

A

photosensitivity and severe disfigurement

21
Q

enzyme involved in ALA dehydratase deficiency

major signs and symptoms: abdominal pain, neurophyschiatric symptoms

A

ALA dehydratase

22
Q

enzyme involved in acute intermittent porphyria

signs and symptoms: abdominal pain, neuropsychiatric symptoms

A

uroporphyrinogen I synthase
PBG deaminase

23
Q

enzyme involved in congenital erythropoetic

A

uroporphyrinogen III synthase

24
Q

enzyme involved in porphyria cutanea tarda

A

uroporphyrinogen decarboxylase

25
Q

enzyme involved in hereditary coproporhyria

A

coproporphyrinogen oxidase

26
Q

enzyme involved in varigate porphyria

A

protoporhyrinogen oxidase

27
Q

enzyme involved in protorphyria

A

ferrochelatase

28
Q

in genetic inheritance they are autosomal dominant WITH THE EXCEPTION OF erythropoietic porphyria which is ________

A

recessive

29
Q

enzyme lesion occuring early in the pathway/ prior to the formation of porphyrinogens

increase ____________ includes major signs of symptoms of abdominal pain and neuropsychiatric symptoms

A

ALA and PBG

30
Q

enzyme lesion occurring LATER in the pathway

increase of _______ and _________ which leads to photosensituvity

A

porphyrinogen and porphyrin derivatives

31
Q

globin is degraded to _______

A

amino acids

32
Q

heme is degraded into ________ enters the ______ pool for reuse

A

iron

33
Q

conversion of ferric heme to biliverdin is catabolyzed by the _______________

A

heme oxygenase system

34
Q

subsequently ___________ reduced biliverdin to bilirubin

A

biliverdin reductase

35
Q

bilirubin: hepatic uptake

in the hepatocytes, it can bind to cytosolic proteins such as: _____ and _______

A

ligandin and protein Y

36
Q

bilirubin: bile secretion

occurs by active transport protein ________

A

MRP 2 MOAT

37
Q

occurs when blood bilirubin exceeds in 1mg/dL (17.1 um/L)

A

hyperbilirubinemia

38
Q

positive reaction of erlich’s test - detection of bilirubin by Van Den Bergh

A

reddish-purple azo compound

39
Q

+ methanol —> ______ reacting ——-> _________ bilirubin: hemolytic jaundice

A

indirect reacting
free (unconjugated) bilirubin

40
Q

classification of hyperbilirubinemia

overproduction of bilirubin: kernicterus and choluric jaundice

A

retention hyperbilirubinemia

41
Q

classification of hyperbilirubinemia

reflux into blood stream because of biliary obstruction

choluric jaundice

A

regurgitation hyperbilirubinemia

42
Q

conjugated hyperbilirubinemia

benign autosomal recessive disorder which conjugated hyperbilirubinemia in childhood or adult life

caused by mutation of gene coding MRP2

A

dubin-johnson syndrome

43
Q

_____________ is a family of enzymes with different substrate specificities, increase the polarity of various drugs and drug metabolites, thereby facilitating their excretion

A

glucoronosyltransferases

44
Q

mutations in the gene that encodes __ CAN RESULT in the encoded enzyme having reduced or absent activity

syndromes include glibert syndrome and two types of crigler najjar syndrome

A

bilirubin UDP-glucoronosyltransferase

45
Q

the severe congenital jaundice and accompanying brain jaundice of ______ syndrome reflect the COMPLETE ABSENCE of hepatic UDP-Glucoronosyltransferase activity

A

type 1 crigler najjar syndrome