hemoglobin and myoglobin Flashcards
blood contains what percentages or RBC?
40%
blood contains what percentages or WBC?
1%
blood contains what percentages or plasma?
59%
Hb ____ o2 in the alveoli in the lungs and dilivers o2 to tissues throughout the body
binds
Hb ____ in maintaining acid-base balancing the body by binding some CO2 produced by metabolism and releasing CO2 when HB reaches the lungs
assists
both functions of hemoglobin are dependent on
partial pressure
myoglobin is synthesized inside
muscle cells
myoglobin stores oxygen in muscles cells for use at times of high/low metabolic demand
high
structure of myoglobin
- single polypeptide chain - 80% alpha helical - closely-packed tertiary structure
structure of hemoglobin
- four polypeptide chains 2 alpha and 2 bets - strong hydrophobic interactions between alpha 1 and beta 1 and alpha ii and beta ii
hemoglobin can bind ____ O2 molecules because it has ____ heme molecules
4; 4
heme molecules are ____ bonded to subunits of myoglobin and hemoglobin
covalently
myoglobin can bind ____ O2 molecules because it has ____ heme molecules
1; 1
hemoglobin subunits have strong/weak ___ interactions between heterodimers alpha 1beta 1 and alpha II and beta II
- weaker polar interactions
HbA
alpha2 beta2; 97-98% of total Hb in adult
HbA2
alpha2 delta 2 1.5-3% of total Hb in adult
HbF
alpha 2 gamma 2; fetal; 1 month gestation until near brith
Hb epsilon
embryonic Hb 1 week post-conception until birth
alpha globin genes are found on ____ chromosome
16
beta globin genes are found on ____ chromosome
11
glycosylation of ____ is a marker for chronically elevated blood sugar
of alpha2beta2 (HbA)
organ progression of Hb generation
yolk sac liver spleen bone marrow
- alpha
- beta
- delta
deletion of the globin gene leads to
thalassemia
thalassemia
imbalance in globin chain synthesis
pyrrole rings
coordinate covalent bonds to Fe2+
hydrophobic/hydrophilic chains from the pyrrole rings interact with the surrounding alpha beta globin chains to stabilize heme binding
hydrophobic
heme belongs to the class of pigments known as
porphyrins
myoglobin binding curve is sigmodial/hyperbolic indicating a single constant affinty for O2
hyperbolic
hemoglobin binding curve is sigmodial/hyperbolic indicating a changing affinty for O2
sigmodial
P50
the parital pressure where 50% of the oxygen binding sites are occupied
hemoglobin exists in two conformational forms
T (taut) and R (relaxed)
the T conformation favors the
deoxy form (O2 release)
the R conformation favors the
oxy form (O2 binding)
O2 is a ____ regulator of Hb O2 binding
positive allosteric
2,3 di-phosphoglycerate (2,3 DPG) AND 1,3 BISPHOSPHOGLYCERATE stabilizes the T/R conformation
T deoxy conformatoin allowing realse of oxygen to the tissues
levels of 2,3 DPG increase
chronic COPD, pregnancy, high altitude, chronic anemia, and pregnancy
levels of 2,3 DPG INCREASE IN HYPOXIA BECAUSE
at lower partial pressure more oxygen will be realsed to tissues
carbonic anhydrase
enzynme that catalyzes
CO2 + H2O –> carbonic acid H2CO3
haldane effect
favors synthesis of CO2 and H2O
bohr effect
favors O2 release, protons bind to the Hb and favor T conformation
increas in pH favors O2
binding
decrease in pH favors O2
release
fetal hemoglobin has a different beta chain that has a higher/lower affinity for O2
higher
HbF binds 2,3 DPG _____ becuase the cavity is not as positively charged
poorly
Hb F has a higher/lower O2 binding affinity than Hb A in the mother
higher
what has the highest affinity for oxygen
myoglobin
over 1100 Hb variants known most are the result of ____ mutations
point that change a single amino acid
the most common Hb variant associated with significant pathology in the US is
betaS variant
beta S variant is caused by
mutation at position 6 of B globin gene which changes Glu6 to Val6
beta S mutation can lead to
sickle cell anemia
which forms more readily carboxyhemoglobin or oxyhemoglobin?
carboxyhemoglobin
compounds that inhibit oxygen binding
cyanide (CN-)
carbon monoxide (CO)
nitrogen dioxide (NO2)
hydrogen sulfide (h2s)
cyanide (CN-)
carbon monoxide (CO)
nitrogen dioxide (NO2)
hydrogen sulfide (h2s)
inhibit hemoglobin by
competitive inhibition
mutations that change any of the 3 aa to make the binding less hydrophobic and more hydrophilic result in
hereditary methemoglobinemia
hereditary methemoglobinemia
characterized by cyanosis (blueish color of the skin) and brown color to blood
cytochrome b5 reductase
Fe3+ –> Fe2+
causes of methemoglobinemia
- mutations in ytochrome b5 reductase
- mutations in pentose phosphate pathway
_____ normally reduces reactive oxygen species thereby preventing formation of methemoglobin
glutathione
