Tuesday, 3 April 2012

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.

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
What led to animals evolving 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.