Download Globular Proteins

Biochemistry
Team 434
Globular Proteins
Respiratory Block
Color index: Red= Important Purple= Addition Orange= Explanation
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What are globular proteins?
Types and functions of globular proteins
Hemoglobin (a major globular protein)
Myoglobin
a, b-globulins
g-globulins (immunoglobulins)
Diseases associated with globular proteins
YOU CAN FIND THEM IN
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Examples:
In Bone matrix and
Muscle fibers.
It gives myoglobin and
hemoglobin the ability to
bind oxygen because of
the presence of iron atom
It also contributes to the
red color found in muscles
and blood
NOTE: dimer is α and β NOT β & β OR α & α.
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❖ Hemoglobin function:
Carries oxygen from the lungs to tissues and carries carbon
dioxide from tissues back to the lungs.
Demonst
ration
Normal level (g/dL):
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Males: 14-16
Females: 13-15
Extra Info:The unliganded (deoxy) form is called the "T" (for "tense or tight")
state has low- affinity for O2 because it contains extra stabilizing interactions
between the subunits. In the high-affinity “R”(for”relaxed”)state conformation the
interactions which oppose oxygen binding and stabilize the tetramer are somewhat
weaker or "relaxed".
Remember by this :
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Tense in Tissue.
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Relaxed in Respiratory
tract.
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Normal Hb
Abnormal Hb
Unable to transport O2 due to it’s abnormal structure
HbA(97%)
HbA2(2%)
HbF(1%)
HbA1c
Carboxy-Hb
HbA
structure
is the
Oxygen
binding to
hemoglobi
n AND it
is found
adults.
appears
about 12
weeks
after
birth.
composed
of 2α ,2 δ
globin
chains.
Major hemoglobin
found in the fetus
and newborn and
its function is
unknown in adults.
Tetramer with 2
α and 2 γ chains.
since it has
Higher affinity
for O2 than HbA,
O2 is
Transferred from
maternal to fetal
circulation across
placenta.
nHbA undergoes
non-enzymatic
glycosylation
spontaneously
depending on
plasma glucose
levels.
high in patients
with diabetes
mellitus.
HbA+glucose=Hb1c
sensitive and
specific marker
for sugar level in
blood
Reversible.
CO replaces
O2 and
binds 200X
tighter than
O2 (in
smokers).
Met-Hb
Sulf-Hb
Reversible.
Irreversible.
becomes normal by
vit.c
When Fa++
(Ferrous)
becomes Fe+++
(Ferric) ~2%
that cannot
carry O2.
get degraded by
enzymes so it’s
enzyme related
Forms due to
high sulfur
levels in
blood
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caused by
1.
2.
3.
• Synthesis of structurally abnormal Hb ( qualitative).
• Synthesis of insufficient quantities of normal Hb ( quantitative).
• Combination of both.
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what is it ?
Defensive proteins
produced by the Bcells of the immune
system
Structure
Y-shaped structure
with 2 heavy and 2
light polypeptide
chains
Function
Neutralize bacteria
and viruses
Types
IgA, IgD, IgE, IgG, IgM
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Globular Proteins
Hemoglobin
Myoglobins
a1,a2,B-globulins
Y-globulins
(Immunoglobulins)
Abnormal
Normal
HbA: Found in adults.
HbA2: Found in adults in little amounts.
HbF: In fetus.
Enzymes
Carboxy Hb: CO2 replaces O2.
Met Hb: Oxidized Fe+++.
Sulf Hb: Sulfur binding with O2.
Hemoglobinopathies:
- Methemoglobinemia: Oxidation of Hb to Ferric. (Chocolate Cyanosis)
- Sickle cell disease (HbS): Glutamic acid replaced by Valine → Sickle cell anemia.
- Hemoglobin C disease: Glutamic acid replaced by lysine → Mild hemolytic anemia.
- Thalassemia: alpha-thalassemia (mild & moderate) OR beta-thalassemia (severe).
Myoglobinuria: Specific marker for muscle injury.
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1-Which of the following is a globular protein?
A- Actin B- Myosin
C- Hemoglobin D- All of the above
2-Which of the following is the major type of
normal Hb?
A- HbA B- HbA2
C- HbF D- HbA1c
3-Which of the following is irreversible?
4-In Met Hb the iron is in the form of …?
A- Carboxy Hb B- Met Hb
A- Ferris
C- Sulf Hb
C- Both of them D- Non of the above
D- Non of the above
5-Which of the following is true about HbA structure?
A- Weak ionic and hydrogen bonds between ab dimer pairs
B- Strong interactions between a and b chains from stable ab
dimer
C- Strong ionic and hydrogen bonds between ab dimer pairs
D- Weak interactions between a and b chains from stable ab
dimer
B- Ferric
6-What is the form in which majority
Carbon dioxide is transported in the
blood ?
A- Bicarbonate B- Carbon Monoxide
C- Both A & B D- Non of the above
7-Which of the following is the major
hemoglobin found in the fetus and newborn?
A- HbA B- HbA2
C- HbF D- HbA1c
8-When does HbA2 appears?
A- 10 weeks after birth B- 12 week after
birth
C- 20 weeks after birth D- 22 weeks
after birth
9-Which of the following Hb doesn’t require
enzyme?
10-HbA1c levels are high in patients with ?
A- HbA B- HbA2
A- Kidney disease B- Heart disease
C- HbF D- HbA1c
C- Diabetes mellitus D- All of the above
11-Methemoglobinemia can
bind oxygen
12-Which of the following is true about myoglobin?
A- T
A- The non-charged amino acids are located on
the surface
B- F
B- The heme group is present at the periphery of
the molecule
C- Myoglobin gives red color to skeletal muscles
D- Supplies oxygen during anaerobic exercise
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Hemoglobin and Hemoglobinopathies
Oxygen Transport
DIFFERENT TYPES OF HEMOGLOBIN
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Nouf AlOraini
Rana AlJunadil
Reema AlRasheed
Sheikhah AlDosari
Jumana fatani
Maha AlRabiah