Chapter 3 Globular Proteins part I Flashcards
1
Q
R form is associated with what ?
Deoxygentated or Oxygenated ?
A
Oxygenated
2
Q
what major type of hemoglobin is found in adults ?
A
Hemoglobin A
HbA
3
Q
Bohr Effect
A
- the presence of CO2/H+ affects the affinity of hemoglobin towards Oxygen
- Increased attraction of hemoglobin to oxygen
- more presence of Co2 or H increases the love for Oxygen
4
Q
when hemoglobin is on it’s T form what is going on ?
A
The molecule is TENSED
movement is constrained by ionic and hydrogen bonds
5
Q
Structure of Heme
- what is held in the center of heme by four nitrogens ?
- how many bonds can heme-Fe+2 form?
- where are these two bonds coordinated ?
A
- Iron (Fe+2)
- two bonds
- side chains of histidine** residue **of the globin molecule
6
Q
T form is associated with
Deoxygenated or Oxygenated ?
A
Deoxygenated
7
Q
2,3-BPG
A
- allosteric effector
- affects the affinity of hemoglobin towards oxygen
- high levels of BPG is found in COPD, chronic hypoxia
- decrease attraction to oxygen
- the removal of BPG returns the affinity of hemoglobin to oxygen
8
Q
Myoglobin Stucture and Function
- which major organs/tissues contain hemeproteins?
- how many O2 molecules can myglobin bind ?
- describe the interior of myoglobin (what is found) ?
- how is this protein stabilized ?
- how many polypeptides are involved with this protein?
- most of this polypeptide chain is folded in how many stretches ?
- Does myoglobin have more than one heme group ?
A
- skeletal and cardiac
- one O2 molecule
- non-polar bonds
- by hydrophobic interactions
- single chain of polypeptide
- EIGHT stretches of alpha helix
- no ! it only contains ONE heme group
9
Q
Binding Heme Group of Myoglobin
- what does the first histidine bind directly to ?
- what is the role of second histidine ?
- Does second histidine have interaction with heme ?
A
- Fe+2 of heme
- stabilize the O2 binding with Fe+2
- no
10
Q
Quatinary Structure of Hemoglobin
- what is a dimer ?
- name the two dimers involved in this structure?
- how are the two dimers held together ?
- when there are TWO dimers how many total molecules are at play ?
- The Two dimers occupy certain positions; what are they?
- the molecule is allowed for movement when there are what kind of interactions in exactly what part?
A
- a molecule or molecular complex consisting of two identical molecules linked together
- AlphaB1 and Alpha B2
- by hydrophobic interactions
- four chains are involved
- deoxyhemoglobin and oxyhemoglobin
- weak interactions in between dimers
11
Q
- When hemoglobin is in its R form; explain what is happening at this point ?
- How else can you describe the state of the R form ?
A
- Biding of oxygen to hemoglobin causes rupture of the polar bonds between the 2 dimers
* These ruptures allow for movement - relaxed : with High-oxygen-affinity (oxyhemoglobin)
12
Q
define the major role of hemoglobin ?
A
O2 transport
13
Q
Please finish the sentence:
- An oxygen saturation curve measures oxygen at different
- which hemeprotein has a higher Po2 level in ALL Po2 values ?
- The partial pressure to achieve half saturation (P50) of binding sites is: (state which heme group belongs to the corresponding stated values below :
-1 mmHg
26 mmHg
A
- partial pressures (Po2)
- myoglobin
- myoglobin hemoglobin
14
Q
Hemeproteins
- hemeproteins contain a constituent other than the amino acid, what is this constituent ?
- name the two most abundant proteins ?
- what is the shape/ configuration of hemeproteins ?
- define their binding ability with O2?
A
- prosthetic group
- myoglobin and hemoglobin
- three dimensional
- can be reversible
15
Q
Allosteric Effectors
A
- factors that affect regulation and cooperativity of hemoglobin binding capacity
- pH
- temperature
- PO2 (Co2)
- DPG/ 2,3-BPG
effects on highs and lows on these factor can result in shifting reactions to the RIGHT (less affinity for oxygen) or to the LEFT (high affinity for oxygen)
