MYOGLOBIN AND HEMOGLOBIN Flashcards
n iron-containing cyclic
tetrapyrrole linked by methyne bridges
heme
resides at the center of the planar tetrapyrrole.
ferrous or ferric
ferrous iron (Fe 2+)
proteins with metal-containing tetrapyrrole prosthetic groups
cytochromes (Fe and Cu) and chlorophyll (Mg)
Angle of bond that links the O2 and myoglobin
121
Angle that separates the 2 atoms of oxygen and electrons that are coplanar
(Left)
120
Separates the pairs of electron and triple bonds that are arranged in linear fashion
(Right)
180•
The oxygen-binding curve for myoglobin
Hyperbolic
Load O2 readily at PO2 of lung capillary bed (100mmHg)
Myoglobin or hemoglobin?
Myoglobin
Amount of Bound O2 at PO2 released in active muscle
20mmHg (capillary; active muscle)
40mmHg (other tissues; mixed venous O2 tension)
100mmHg (arterial)
mmHg of of PO2 released during strenous exercise
5 mmHg (required for cytochrome oxidase)
(HbA; normal adult hemoglobin)
α2β2
(HbF; fetal hemoglobin)
α2γ2
α2βS2
(HbS; sickle cell hemoglobin)
HbA2
; a minor adult
hemoglobin
α2δ2
hemoglobin to maximize both the
quantity of O2
loaded at the PO2 of the lungs
cooperative
binding
values of P50
for HbA and
HbF are 26 and 20 mm Hg
P50
-partial pressure of O2
a hemoglobin that carries CO2 to venous blood
carbamates
formed in erythrocytes by the hydration of CO2
to carbonic acid (H2CO3)
cabonate or bicarbonate ?
bicarbonate
changes the charge of amino terminal
carbamate
coupling of the interconversion of CO2 and H2CO3
Bohr effect.
drives the conversion of bicarbonate to carbonic acid
His 146 or His 147 ?
his 146
stabilizes deoxygenated (Tstate) hemoglobin by forming additional salt bridges that must be broken prior to conversion to the R state.
BPG
A mutation that compromise biologic function
HEMOGLOBINOPATHY or thalassemia?
hemoglobinopathy
the heme iron is ferric rather than ferrous
methemoglobinemia or hemoglobinuria
methemoglobinemia
tissue hypoxia with increased RBC
polycythemia
nonpolar amino acid valine has replaced the polar surface
residue Glu6 of the β subunit
Hemoglobin S “STICKY PATCH”
Hb A also provides sticky patch
Treatment for sickle cell disease
Inducing HbF expression to inhibit the
polymerization of HbS,
myoglobin released in urine following myocardial infarction
myoglobinuria
the partial or total
absence of one or more α or β chains of hemoglobin
myoglobinuria or thalassemia ?
Thalassemias
remains in blood for 6-8weeks.
for DM
GLYCATED HEMOGLOBIN (HbA1c)
a consequence of cooperative interactions
in the tetramer
sigmoid or myoglobin
Sigmoidal hemoglobin
organic molecules that
contain four five-membered heterocyclic
(pyrrole) rings, linked in a cyclic or linear
array.
TETRAPYRROLES or trigly
TETRAPYRROLES
One binding of O2 in one subunit
permits successive and easier
binding of O2 for other subunits
ALLOSTERIC EFFECT
affinity of Hb for H+ and CO2 is affected by
changes in Hb-O2 saturation
HALDANE EFFECT
Dec. O2 and pH, Inc. CO2
Bohr effect
Dec. O2 and pH, Inc. CO2
Bohr effect
“tissue”
Dec. CO2, INC. O2 and pH
Haldane effect
“lungs”
Caused by the uptake of O2 in the lungs.
Haldane Effect
His F8 is replaced by tyrosine
Forms a tight ionic complex that stabilizes Fe3+ state
Hemoglobin M
an odorless, colorless gas, which can cause sudden illness and
death, is produced any time a fossil fuel is burned.
CO gas is readily absorbed and is unchanged by the lungs
CARBON MONOXIDE
