PORPHYRIN CHEMISTRY AND METABOLISM

Question 1

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

Answer 1

methyne bridges

Question 2

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

Answer 2

double bounds

Question 3

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

Answer 3

metal ions
nitrogen

Question 4

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

Answer 4

chlorophyll

Question 5

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

Answer 5

ALA and PBG

Question 6

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

Answer 6

porphyrias

Question 7

transport of oxygen in blood

Answer 7

hemoglobin

Question 8

storage of oxygen in muscle

Answer 8

myoglobin

Question 9

involvement in electron transport chain

Answer 9

cytochrome c

Question 10

hydroxylation of xenobiotics

Answer 10

cytochrome P450

Question 11

degradation of hydrogen peroxide

Answer 11

catalase

Question 12

oxidation of tryptophan

Answer 12

tryptophan pyrrolase

Question 13

heme is synthesized from ______– and _______

Answer 13

succinyl coa and glycine

Question 14

type III uroporphyrinogen uses the enzyme

Answer 14

Uroporphyrinogen III synthase

Question 15

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

using the enzyme _______

Answer 15

mitochondria

coproporphyrinogen oxidase

Question 16

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

Answer 16

ferrous iron
ferrochelatase

Question 17

heme synthesis in most mammalian cells with the exception of ________

Answer 17

mature erythrocytes

Question 18

hepatic form of ALA synthase

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

Answer 18

ALAS1

Question 19

erythroid form of ALA synthase

Answer 19

ALAS 2

Question 20

____________ and ____________ exhibited by some patients with congenital erythropoetic porphyria

Answer 20

photosensitivity and severe disfigurement

Question 21

enzyme involved in ALA dehydratase deficiency

major signs and symptoms: abdominal pain, neurophyschiatric symptoms

Answer 21

ALA dehydratase

Question 22

enzyme involved in acute intermittent porphyria

signs and symptoms: abdominal pain, neuropsychiatric symptoms

Answer 22

uroporphyrinogen I synthase
PBG deaminase

Question 23

enzyme involved in congenital erythropoetic

Answer 23

uroporphyrinogen III synthase

Question 24

enzyme involved in porphyria cutanea tarda

Answer 24

uroporphyrinogen decarboxylase

Question 25

enzyme involved in hereditary coproporhyria

Answer 25

coproporphyrinogen oxidase

Question 26

enzyme involved in varigate porphyria

Answer 26

protoporhyrinogen oxidase

Question 27

enzyme involved in protorphyria

Answer 27

ferrochelatase

Question 28

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

Answer 28

recessive

Question 29

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

Answer 29

ALA and PBG

Question 30

enzyme lesion occurring LATER in the pathway

increase of _______ and _________ which leads to photosensituvity

Answer 30

porphyrinogen and porphyrin derivatives

Question 31

globin is degraded to _______

Answer 31

amino acids

Question 32

heme is degraded into ________ enters the ______ pool for reuse

Answer 32

iron

Question 33

conversion of ferric heme to biliverdin is catabolyzed by the _______________

Answer 33

heme oxygenase system

Question 34

subsequently ___________ reduced biliverdin to bilirubin

Answer 34

biliverdin reductase

Question 35

bilirubin: hepatic uptake

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

Answer 35

ligandin and protein Y

Question 36

bilirubin: bile secretion

occurs by active transport protein ________

Answer 36

MRP 2 MOAT

Question 37

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

Answer 37

hyperbilirubinemia

Question 38

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

Answer 38

reddish-purple azo compound

Question 39

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

Answer 39

indirect reacting
free (unconjugated) bilirubin

Question 40

classification of hyperbilirubinemia

overproduction of bilirubin: kernicterus and choluric jaundice

Answer 40

retention hyperbilirubinemia

Question 41

classification of hyperbilirubinemia

reflux into blood stream because of biliary obstruction

choluric jaundice

Answer 41

regurgitation hyperbilirubinemia

Question 42

conjugated hyperbilirubinemia

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

caused by mutation of gene coding MRP2

Answer 42

dubin-johnson syndrome

Question 43

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

Answer 43

glucoronosyltransferases

Question 44

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

Answer 44

bilirubin UDP-glucoronosyltransferase

Question 45

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

Answer 45

type 1 crigler najjar syndrome