Respiratory Pigments Flashcards
What are respiratory pigments?
Proteins that increase the oxygen carrying capacity of the blood
What type of proteins are respiratory pigments?
Metalloproteins
What do respiratory pigments do?
They contain metal ions that reversibly binds to oxygen to increase the amount of oxygen able to be transported by the blood
Why do respiratory pigments have colour?
The metal ion
How do respiratory pigments increase the blood carrying capacity of oxygen?
They take oxygen out of solution and maintain the pressure gradient from the respiratory surface to the blood
What are the 3 types of respiratory pigments found in animals?
Hemoglobin, chlorocruorins and hemocyanins
What colour is hemoglobin? What metal ion does it use to bind oxygen?
Red, uses iron in a heme group
Is hemoglobin intracellular or extracellular?
Can be either
What colour are chlorocruorins? What metal ion does it use to bind oxygen?
Green-ish red. They use iron, but not as a heme
What organisms are chlorocruorins found in?
A few families of marine worms
Are chlorocruorins intracellular or extracellular?
Extracellular
Are chlorocruorins related to hemoglobin?
Yes, a subclass of the same family
What colour are hemocyanins? What metal ion does it use to bind oxygen?
Blue. They use copper
What colours are hemocyanins when they are deoxygenated vs oxygenated?
Colourless when deoxygenated and blue when oxygenated
Are hemocyanins related to hemoglobin?
No, they evolved independently
How many oxygen molecules bind per heme?
One
How many subunits and oxygen binding sites are in hemoglobin?
4 subunits: 2 alpha and 2 beta. Each subunit has a heme so 4 oxygen binding sites
What type of binding curve is seen for hemoglobin?
Sigmoidal
Why does hemoglobin have a sigmoidal binding curve?
It shows cooperativity
What state is hemoglobin in when it is deoxygenated? What bonds are stabilizing this state? How much of an affinity for oxygen does it have?
The T state. Stabilized by salt bridges and hydrogen bonds. Low oxygen affinity
What state is hemoglobin in when it is oxygenated? What bonds are stabilizing this state? How much of an affinity for oxygen does it have?
The R state. Stabilized only by hydrogen bonds. High oxygen affinity
Why does oxygen binding cause a conformation change in the hemoglobin subunits?
It weakens the salt bridges
What determines the percentage of hemoglobin saturation?
Partial pressure of oxygen
What is the oxygen partial pressure in the alveoli, cells, and blood?
High pressure in the alveoli, low in the cells and blood
What is the carbon dioxide partial pressure in the alveoli, cells, and blood?
Low pressure in the alveoli and blood, high in the cells
What is pulmonary circulation?
Circulation between the heart and lungs
What is systemic circulation?
Circulation between the heart and the rest of the body
How much of the total oxygen in the blood is carried by hemoglobin (%)?
98.5%
What is the maximum oxygen saturation in the pulmonary and systematic capillaries? Why are they different?
Pulmonary: 97%
Systematic: 75%
Pulmonary circuit has more hemoglobin in it
What defines the affinity of hemoglobin to oxygen?
The P50: the oxygen pressure when hemoglobin is 50% saturated. = Km
What is the oxygen affinity of hemoglobin when P50 is low?
High affinity
What is the oxygen affinity of hemoglobin when P50 is high?
Low affinity
Is P50 constant?
No, changes depends on what is happening in the body
What is the P50 of myoglobin? Why is this an adaptation?
Very low, so it has high affinity to oxygen. It allows myoglobin to pull oxygen off of hemoglobin and into the cells
