Parul University of Medical Sciences & Research
Department of Biochemistry
Topic: Structure of Heme
Presented by:
Rathava Prakruti Umeshbhai
Roll No. 109
Introduction
• Heme is a complex molecule consisting of
porphyrin ring,an iron atom and a side chain
which
plays
a
crucial
role
in
oxygen
transport,electron transfer and catalysis in
various biological processes.
• Heme
is
primarily
biosynthesized
in
erythrocyte producing cells of both the bone
marrow and the liver.
Introduction
Heme is present in:
Myoglobin
Hemoglobin
Cytochromes
Nitric oxide synthase
Catalase
Peroxidase
Structure of Heme
• Heme is a derivative of the porphyrin
• Porphyrins are cyclic compounds formed by
fusion of 4 pyrrole rings linked by methenyl
(=CH-) bridges.
Structure of Heme
• The pyrrole rings are named as I, II, III, IV.
δ
II
α
• The bridges are named as alpha, beta, gamma
and delta.
I
III
γ
β
IV
Types of Porphyrin
• When the substituent groups have a
symmetric arrangement (1,3,5,7 and
2,4,6,8) they are called the I series.
• The III series have an asymmetrical
distribution of substituent groups
(1,3,5,8 and 2,4,6,7).
• The usual substitutions are:
a.propionyl(-CH2-CH2-COOH) group
b.acetyl (-CH2-COOH) group
c.methyl (-CH,) group
d.vinyl (-CH=CH₂) group.
I series Porphyrins
Uroporphyrin I
(A,P, A,P ,A,P ,A,P)
Coproporphyrin I
(M,P, M,P, M,P, M,P)
III series Porphyrins
Uroporphyrin III
(A,P, A,P, A,P, P,A)
Coproporphyrin III
(M,V, M,V, M,P, P,M)
Protoporphyrin III
(M,V, M,V, M,P, P,M)
• Type III is the most predominant in biological systems. It is also called series 9.
Structure of Heme
• Due to presence of Fe at the
centre,the heme is also called
as ferroprotoporphyrine.
Porphyrias
• Porphyrias are a group of rare inherited
blood disorders.
• People
with
these
disorders
have
problems making a heme in their bodies
leading to the accumulation of toxic
intermediates.
• Symptoms
of
porphyrias
are
skin
blustering ,sensitivity and abdominal pain
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