Hemoglobin and Myoglobin Flashcards
Why is hemoglobin needed?
Oxygen has poor solubility in blood
What occurs to iron in free heme when oxygen binds?
Oxygen oxidizes it from Fe2+ to Fe3+
What is methemoglobin (metHb)?
Hemoglobin that contains oxidized iron (Fe3+)
What reduces metHb to Hb?
Cytochrome b5 reductase (methemoglobin reductase); needs to stop metHb from accumulating
What is methemoglobinemia?
When methemoglobin rises higher than 20% in the blood (normally 1%)
What are the two types of inherited methemoglobinemia?
Type 1: Defective reductase (recessive)
Type 2: Hemoglobin M; defective hemoglobin (dominant)
Vitamin C is preventative of this disease
How can methemoglobinemia be acquired?
Anesthetics
Nitrites (infants consume too many)
Antibodies
What is the Bohr Effect on hemoglobin?
Decreasing of local pH decreases the binding of hemoglobin so that oxygen can be released to the cells that need it
What is the Bohr effect on myoglobin?
Decreased local pH increases the amount of oxygen transferred to myoglobin
What is the effect of CO2?
It decreases pH and forms carbaminohemoglobin stabilizing the T state
What is the effect of 2,3-BPG on hemoglobin?
Decreases affinity for oxygen
Where does 2,3-BPG come from?
It is an intermediate in glycolysis; increased exercise increases levels of 2,3-BPG causing more oxygen to be released
What is the importance of His E7?
Interacts with oxygen to stop it from reacting with the iron; without E7 CO has much higher affinity than O2
Why is important to note about methemoglobin?
It cannot bind oxygen
What does hemoglobin do with iron?
Doesn’t allow oxygen to oxidize it
