L8 Flashcards
What 2 proteins are responsible for O2 storage and transport?
hemoglobin and myoglobin
what is hemoglobin?
hemoglobin is the red blood pigment exclusively present in erythrocytes(RBC)
List all 4 types of hemoglobin that are synthesized in the human body throughout its life span and explain when they are present . .
Hbε(epsilon) :Present in embryonic life ( Hb Gower-1). Composed of 2 - ζ(zeta) and 2 - ε chains.
HbF:Fetal stage (Second trimester till birth). Composed of 2 – α and 2 – γ chains.
Hb A1:Major normal adult Hb (Starts with birth and reaches completion by around 6 months). Composed of 2 - α and 2 - β chains.(gamma gene is almost off)
Hb A2:Minor normal adult Hb Composed of 2 - α and 2 - δ (delta) chains.
what is the normal adult blood content?
Hb A1 - 97%
Hb A2 - 2%
Hb F - 1%
what is the function of hemoglobin of hemoglobin and myoglobin ?
hemoglobin transports blood
helps with transport co2 from tissues to lungs
acts as buffer
while myoglobin stores it . if there is not enough hemoglobin then hemoglobin anemia will occur
how many oxygens can hemoglobin and myoglobin bind too , how many chains do they have ?
hemoglobin can hold 4 oxygens while myoglobin can only hold 1
all hemoglobin are hetro-tetramere
.
describe the structure of hemoglobin A1
IT IS A CONJUGATED PROTEIN . HEME BEING THE PROSTHETIC GROUP
Globin (96% of Hb)
4 polypeptide chains of two different primary structures (2 - α and 2 - β chains)
Each chain has one heme group attached to it.
What is the heme inside the ?
complex of iron Fe++ ferrous and protoporphyin (has 4 pyrrole rings )
what are the 6 bonds Fe++ forms ?
4 with the N of porphyrin.
On one side of the plane with a.a histidine (proximal) of the globin.
The other side with O2.
1 Hb can bind and transport 4 O2
describe the structure of a myoglobin.
conjugated protein with prosthetuic group being skeletal muscles and cardiac muscles
consists of one pollypeptide chain (monomeric)
has 1 molecule of heme attached
In the muscles:
Mb acts as an O2 storage protein in muscles.
O2 is taken up and stored by Mb.
Mb has high affinity for O2 than Hb.
.
the ODC for myoglobin is?
hyperbolic . it shows high affinity for oxygen (uptight)
the ODC for hemoglobin is ?
sigmoidal. has comparatively low affinity for oxygen. this also indicates that binding of O2 to Hb is cooperstive . binding of O2 to one heme increases binding affinity of O2 to other hemes of the same Hb molecule
there is communication among subunits in the hemoglobin function
..
what major forms are co2 present in the body.
Dissolved CO2
Bicarbonate (HCO3-)
Carbaminohemoglobin (Carbon dioxide linked to hemoglobin)
explain co-operative bining.
binding of O2 to one heme increases binding affinity of O2 to other gmes of the same Hb molecule . thgis occurs because there is communication among subunits in the hemoglobin function
