Lecture 4 Biochem

Question 1

Hemoglobin has how many Heme groups?

Answer 1

4 Heme groups; Tetrameric.

Question 2

What kind of structure is Hemoglobin?

Answer 2

Quartenary Structure

Question 3

What is the FXN of Hemoglobin?

Answer 3

It’s a transport protein for O2.

Question 4

Hemoglobin is dependent on what? Due to this what kind of curve does it display??

Answer 4

Hemoglobin is dependent on O2, thus it displays a sigmoidal curve.

Question 5

Sigmoidal Curve is for what protein? What does this mean?

Answer 5

Hemoglobin. Great grabber of oxygen when oxygen concentration is HIGH and really good at releasing oxygen to tissues when oxygen concentration is LOW.

Question 6

Hemoglobin has how many alpha and beta sub units?

Answer 6

2 Alpha subunits 2 Beta-hemoglobin subunits 4 Heme group

Question 7

Hemoglobin has what cooperativity?

Answer 7

h>1 ; cooperative, sigmodial curve

Question 8

Where is Hemoglobin found?

Answer 8

In the blood.

Question 9

At HIGH oxygen levels, Hemoglobin’s affinity for oxygen is?

Answer 9

High.

Question 10

At LOW oxygen levels, Hemoglobin’s affinity for oxygen is?

Answer 10

Low.

Question 11

Kinetics for Hemoglobin binding. What does the first ligand cause for the next ligand?

Answer 11

The binding of the first ligand causes conformational change for the next ligand to bind easier.

Question 12

Taut, what form of oxygen in?

Answer 12

Deoxygenated!

Question 13

Relaxed, what form of oxygen in?

Answer 13

Oxygenated!

Question 14

In the lungs, hemoglobin is bound to?

Answer 14

Lungs = High Con of O2 Thus, more hemoglobin bound to Oxygen.

Question 15

In the tissues, hemoglobin is bound to?

Answer 15

Tissues= Low conc of O2. Thus, less hemoglobin bound to Oxygen.

Question 16

The steps in conformational change in hemoglobin.

Answer 16

1)O2 binds 2)Pulls Fe up to fit into the plane 3)prox HIS is moved 4)Alpha helix is moved 5)Alters neighboring subunit conformation at alpha- beta interface 6)Neighbor now has increase affinity for oxygen

Question 17

Myoglobin and Hemoglobin is made up of mostly

Answer 17

Alpha Helices Globular Protein

Question 18

One heme groups has how many pyrrole rings? What is this called? What does it bind to?

Answer 18

4 Pyrrole rings, tetrapyrrole and binds to Fe within the same plane.

Question 19

Iron is a ___ and it can bind to how many ligands?

Answer 19

tetrahedral and can bind 6 ligands.

Question 20

One Heme Subunit has what attached to it?

Answer 20

Distal Histidine Is too far away cannot bind iron leaving the 6th position unbound for O2 Proximal Histidine Binds iron

Question 21

Myglobin has how many heme groups?

Answer 21

One heme group.

Question 22

What kind of structure does Myglobin have?

Answer 22

Tertiary Structure

Question 23

Where is myglobin found in the body? Fxn?

Answer 23

In tissues, as as stroage protein.

Question 24

Myglobin has what kind of curve ? Affinity for oxygen?

Answer 24

A hyperbolic cure, affinity for oxygen is always HIGH, regardless of O2 concentration.

Question 25

Myoglobin has what type of cooperativity?

Answer 25

h=1, non-cooperative. Each subunit has the same affinity for oxygen.

Question 26

Hill equation is used for? What is Myglobin and Hemoglobins?

Answer 26

Used to find degree of O2 binding to hemoglobin Greater than one it indicates cooperativity h\>1, hemoglobin h=1, no cooperativity, myoglobin

Question 27

Bohr Effect determines?

Answer 27

Determines if Hemoglobin needs to release oxygen due to the pH and CO2 concentration in tissues.

Question 28

When Ph drops and CO2 concentration increase, what shift will the curve make?

Answer 28

A shift to the right, to decrease hemoglobins affinit for oxygen and allow it to be released more easily.

Question 29

2,3 BPG has what effect on the Bohr curve?

Answer 29

Stabilizies the taut confirmation, and shifts the curve to the right.

Question 30

how many pyrrole rings does heme have?

Answer 30

4 pyrrole rings = tetrapyrrole.

Question 31

Within a alpha helix when the Ph drops

Answer 31

Taut (deoxy) hemoglobin conformation is favored when HIS is protonated. Due to When the ph drops, beta HIS becomes protonated and is stabilized by the negative of beta aspartate. This maintains the (taut) deoxygenated confirmation This decreases oxygens affinity O2 is released Stabilizes a critical salt bridge that tends to maintain hemoglobin in the deoxy T state

Question 32

Within an alpha helix when the CO2 is in high concentration

Answer 32

CO2 interacts with amino terminal of alpha subunits and that will create this carbamate that has a negative charge. Then carbamate interacts with positively charged amino acids Stabilizes the deoxygenated state Releases O2 Salt links stabilize the T state of hemoglobin

Question 33

Everything about 2,3 Biphosphoglycerate

Answer 33

Negative allosteric effector Floats around in our blood has a negative 5 charge to it Going to interact with 3 positively charged groups on each Beta chain 2,3 BPG binds to hemoglobin by 2 Beta subunits. Stabilizes the deoxyhemoglobin confirmation Oxygen does not bind as tightly in blood due to 2,3 BPG. Interacts with B chains 8 + charged group on B chains stabilize the 5 - charges on 2,3 BPG

Question 34

Hemoglobinopathies

Answer 34

Categories as most prominent changes to protein structure and fxn and regulation

Question 35

HbC (common)

Answer 35

Abnormal solubility, Mild Anemia.. Enlarged spleen.. Decrease RBC

Question 36

Hb titusivlle

Answer 36

Decrease O2 affinity, Mild Cyanosis

Question 37

HbM boston (Rare)

Answer 37

Ferric Heme ( fe 3+) instead of ferrous heme (fe 2+), Cyanosis of skin and mucous membranes.

Question 38

Kinetics for Hemoglobin

Answer 38

Tetrameric protein Bind first ligand cause conformational change for the next ligand to bind easier More ligands bound strength increases

Question 39

Which of the following is true about both myoglobin AND hemoglobin? ## Footnote They are composed mostly of alpha helical proteins They are both only found in the tissues They both have sigmoidal curves They are both tetrameric proteins

Answer 39

They are composed mostly of alpha helical proteins

Question 40

When 2,3-BPG is bound to hemoglobin: The curve shifts to the left and oxygen affinity increases The curve shifts to the right and oxygen affinity decreases The curve shifts to the left and oxygen affinity decreases The curve shifts to the right and oxygen affinity increases

Answer 40

The curve shifts to the right and oxygen affinity decreases

Question 41

Which of the following indicates that a protein shows cooperativity? Hill coefficient = 0 Hill coefficient = 1 Hill coefficient = 2 Hill coefficient = 0.27

Answer 41

Hill coefficient = 2

Question 42

Which of the following is NOT true about myoglobin? It has a hyperbolic curve It binds oxygen on its heme group It has a sigmoidal curve It is a monomer

Answer 42

It has a sigmoidal curve

Question 43

All of the following directly interact with the iron in a heme group EXCEPT: Proximal histidine Porphyrin rings Oxygen Distal histidine

Answer 43

Distal histidine