Heme Flashcards Preview

Biochemistry MBS > Heme > Flashcards

Flashcards in Heme Deck (17):
1

pyrophyrias

-diseases associated with defects in heme synthesis

2

jaundice in newborns

-defects in heme breakdown

3

porphin is composed of what

-4 pyrroles
-porphyin ring is the same in all porphyrins

4

what is heme in chemical terms

-a protoporphyrin with an iron atome

5

what distinguishes the porphyrins?

the sidechains on the pyrrole

6

how do type 1 and type 3 porphyrins differ

-type 3 is physiologic, its ring D is asymmetric to the other rings
-type 1 is a harmful biproduct which can result from deficiencies in heme synthesis

7

problems with protoporphyrinogen 3

-intermediates in heme synthesis
-can spontaneously oxidize and creat protoporhpyrin which is a conjugated double bond system
-can cause deposits in the skin, photosensitivity, and neurotoxicity
-oxidized product is insoluble, difficult to excrete

8

protoporphyrin

this is the porphyrin of heme
-oxidized and has side chains

9

heme is required for what molecules

-hemoglobin (most of the heme made is used for this and is made in pre-RBC cells
-cytochromes
-catalase
-peroxidase

10

aminolevulinate synthase

-this is the first step in heme prduction
-heavily regulated
-occurs in the mitochondria
-condenses glycine and succinyl CoA to make delta ALA
-slowest reaction in heme synthesis
-product is transported to the cytoplasm

11

co synthase deficiency

-this enzyme is typically responsible for uroporphyinogen type 3
-if defficient, uroporphyrinogen type 1 is formed which can be converted to coprophorynogen type 1
-these can be oxidized into conjugate double bond systems which deposit in the skin causing photosensitivity and is neurotoxic

12

ALAS1 inhibitors

-found in the liver
-heme: allosteric, decreased mRNA stability, inhibits ALAS1 transport into mitochondria
-insulin: decreases transcription of ALAS1

13

ALAS1 promoters

-found in the liver
-steroid hormones: increases ALAS1 expression
-cyt p450: upregulate heme synthesis

14

ALAS2 inhibitors

-found in bone marrow
-heme: inhibits transport into the mitochondria

15

ALAS2 promoters

-found in the bone marrow
-iron: increase translation of ALAS2 by removing an inhibitor from mRNA
-increase ferrochelatase activity
-transcription factors: coordinate globin genes and ALAS2 transcription

16

prophyrias
-mech
-therapy
-important management

-accumulation of toxin intermediates up to a point of a defect
-treated by decreasing activity of ALAS (can not give patient steroid hormones)
-important to eliminate conditions leading to increased use of free heme, CYPP450 reactive drugs

17

porphyria cutanea tarda

-vampires
-deficiency in uroporphyrin decarboxylase