Myoglobin Hemoglobin

What is the structure of myoglobin

Monomeric protein, has 8 alpha-helices, and binds oxygen in muscles

What is the structure of hemoglobin

Tetramer( 2 alpha, 2beta subunits) and binds oxygen in the blood

How does heme bind oxygen

Heme’s iron binds one oxygen molecule and oxygen binds reversibly

How do oxygen saturation curves differ for myoglobin and hemoglobin

Myoglobin: higher oxygen, higher affinity and responds to muscles’s O2 needs

Hemoglobin: Sigmoidal curve (cooperative binding, responds to O2 availability

How does hemoglobin show cooperativity?

It changes between T (low affinity) and R (high affinity) states, also oxygen binding increases affinity

How does oxygen affinity differ between myoglobin and hemoglobin?

Myoglobin: High affinity, stores oxygen

Hemoglobin: Lower affinity, releases oxygen to tissues

What are the effects of oxygen affinity differences?

A rightward shift of the curve that hemoglobin has a decreased affinity for oxygen, oxygen actively unloads

A shift to the left shows increased hemoglobin affinity for oxygen and an increased reluctance to release oxygen

What is the Bohr effect?

A decrease in pH and increase in carbon dioxide levels reduces hemoglobin’s ability to bind oxygen.

How does BPG affect hemoglobin

by binding to hemoglobin, 2,3-BPG decreases hemoglobins affinity for oxygen, so shifting the entire oxygen-binding curve to the right side

What’s the function of myoglobin vs hemoglobin?

Myoglobin stores oxygen in muscles and hemoglobin transports oxygen in blood

Enzyme

They decrease the activation energy of the reaction

When something is binding more TIGHTLY it means…

The answer is going to have a lower Km

Acid>Base

the answer will be less than pka

Highest boiling point

-OH is alcohol which can H-bond

IMF responsible between enzyme and amino acid residue

• Leu, Val (alkyl, nonpolar) would be London Forces

• Asp, Glu (charged) would be Ionic Bond

• Ser, Asn (H donors + Lone pairs) would be Hydrogen Bonding

The difference between specificity and catalytic residues in enzymes

Specific: contribute to enzymes unique function and it’s ability to bind things within it’s binding site

Catalytic: directly involved in the chemical reaction that the enzyme is catalyzing

What is the Bohr effect?

The Bohr effect becomes the active tissue more acidic causes Hb O2 affinity to decrease, affects Hemoglobin subunits to transport oxygen. Hb in the graph would go right.

The difference between competitive and noncompetitive inhibitors

Competitive goes to the active site and blocks the substrate from binding, while non competitive goes to allosteric site is binded at instead.

Remember this: BPG binds and stabalizes….

BPG stabilizes the Hb T state. At high PO2 in the lungs, Hb is fully saturated with oxygen. At lower PO2, Hb will release more oxygen than it would if no BPG were present . Fetal Hb os affected less by BPG than adult adult Hbcannot

Cannot bind O2

apomyoglobin and apohemoglobin