The Difference between Hemocyanin and Hemoglobin
What is Hemocyanin?
Hemocyanin is a respiratory
protein, much like Hemoglobin. However, Hemocyanin contains copper instead of
iron, which gives the blood of animals with Hemocyanin blue instead of red.
What animals have Hemocyanin?
Most molluscs and arthropods contain
Hemocyanin, such as the horseshoe crab and the giant octopus.
Differences
Hemocyanin
|
Hemoglobin
|
Preforms better in cold environments with
low oxygen pressure
|
Preforms
better in oxygen rich environments
|
Contains copper held by a cluster
|
Contains iron held
inside of a ring
|
Binds with oxygen non co-operatively most
of the time (when non co-operativly, is one quarter as efficiant as hemoglobin) |
Binds
with oxygen co-operatively all of the time
|
Free floating in blood
|
Connected to red
blood cells
|
 |
| A model for hemoglobin Hemoglobin binds co-operativly with another hemoglobin, connected by two oxygen, much like the picture below of hemocyanin. |
Because Hemocyanin is less
effective in most areas, people might wonder why any animal have Hemocyanin at
all. The answer is that Hemocyanin is better than Hemoglobin in lower oxygen
environments, such as at the bottom of certain oceans/seas, where the creatures
with Hemocyanin live. Also Hemocyanin preforms better at colder temperatures,
again where these molluscs and arthropods live.
Scientists
believe that the Hemocyanin trait split off from the Hemoglobin trait around 600 million years ago.
 |
| A model for hemocyanin Most hemocyanin's bind with oxygen non co-operativly, but this is a model of two of them binding co-operativly. |
Bibliography
