Md2 Block4 Biochem L 40 Metabolism Of Amino Acids Conversion Part A

Front 1

porphyrins are cyclic compounds that readily bind

Back 1

metal ions, usually Fe2+ or Fe3+

Front 2

most prevalent porphyrin is =


rapidly turned over – 6 g of___ turned over every day

Back 2

heme

Hb

Front 3

cyclic structures formed by linkage of 4 pyrrole rings through methylene bridges

Back 3

different porphyrins have different side chains attached to the pyrrole rings:

Front 4

________ has acetate and propionate side chains

_________ has methyl and propionate side chains

Back 4

uroporphyrin

coproporphyrin

there are 4 ways side chains can be distributed around the pyrrole rings, roman numerals I-IV

Front 5

in humans, only ___ ___ ___ are physiologically important

Back 5

type III porphyrins

Front 6

type __ porphyrins may build up in some diseases

Back 6

1

_______ are the reduced precursors of porphyrins that are colourless – intermediates in heme synthesis

Hint 6

porphyrinogens

Front 7

_______is the final product of porphyrin biosynthesis

Back 7

heme


heme consists of one ferrous (Fe2+) ion coordinated in the center of the pyrrole rings of =

Hint 7

protoporphyrin IX

Front 8

Heme Biosynthesis - Overview

The rate limiting synthetic step is the formation of d- aminolevulinic acid (ALA) from glycine and succinyl CoA

Back 8

Several key steps take place in mitochondria or on mitochondrial membranes.

porphyrinogens are colorless, unstable, ringed tetrapyrroles that are readily and irreversibly oxidized to___ ___ ___, which are excreted in urine or bile.
only one porphyrin, protoporphyrin IX, is retained and is converted to heme.

Hint 8

red, stable porphyrins

Front 9

Sites of Heme Biosynthesis=

Back 9

Liver – primarily cytochrome P450

Erythropoietic cells (RBC precursors) of the bone marrow - hemoglobin

Front 10

Sites of Heme Biosynthesis

first reaction and last 3 reactions happen in_____
rest in _______

Back 10

mitochondria

cytosol

Front 11

Formation of d-aminolevulinic acid (ALA)

all carbons and nitrogens from glycine and succinyl CoA

catalyzed by

Back 11

ALA synthase – requires

______ coenzyme (derived from B6)

*** rate-limiting step

Hint 11

pyridoxal phosphate

Front 12

ALA synthase is inhibited by =
2ct

Back 12

heme

hemin

Hint 12

Front 13

Drugs that increase ALA synthase activity:
drugs metabolized by

Back 13

cytochroms P450 ...
monoxygenase system

↓ heme levels drop in liver

↑ synthesis of ALA synthase

↑ synthesis of ALA

Front 14

Step 1: Formation of ALA

Back 14

Step 2: Formation of porphobilinogen

Hint 14

Step 3: Formation of uroporphyrinogen III

Front 15

Step 4: Formation of coproporphyrinogens

Back 15

Step 5: Formation of protoporphyrinogen IX

Hint 15

Step 6: Formation of protoporphyrin IX

Front 16

Step 7: Formation of heme

ferrochelatase requires iron (II), ascorbic acid and
cysteine (reducing agents).
ferrochelatase is inhibited by lead.

Back 16

Summary of Heme Biosynthesis

Front 17

Summary of Heme Biosynthesis
7 Steps

Back 17

Each step is formation of::::

Step 1: ALA
Step 2: porphobilinogen
Step 3: uroporphyrinogen III
Step 4: coproporphyrinogens
Step 5: protoporphyrinogen IX
Step 6: protoporphyrin IX
Step 7: heme

Hint 17

ALA
porphobilinogen
uroporphyrinogen III
coproporphyrinogens
protoporphyrinogen IX
protoporphyrin IX
heme