- Hemoglobin (Hgb) is the iron-containing oxygen-transport metalloprotein in the red blood cells of almost all vertebrates as well as the tissues of some invertebrates.
- The research focused on the fact that all globins descended from a common protein ancestor.
- According to the research, the evolutionary lines of human and shark separated 400 million years ago.
Breakthrough research has been released from US and UK biologists who conjointly found the origin of hemoglobin and were able to synthesize proteins that were its ancestors. Hemoglobin (Hgb) is the iron-containing oxygen-transport metalloprotein in the red blood cells of almost all vertebrates as well as the tissues of some invertebrates. Hemoglobin in blood carries oxygen from the lungs or gills to the rest of the body.
The new research came to the conclusion that there were two key mutations. All modern land vertebrates and almost all marine vertebrates, with the exception of a hundred species, belong to the jawed group (Gnathostomata). They are distinguished not only by the jaws, but also by the structure of their hemoglobin. It is incredibly efficient at carrying oxygen. Undoubtedly, this was one of the main evolutionary trumps of the jawbones, which allowed them to occupy the upper levels of all food chains on land and in the sea.
Jawbone hemoglobin is a protein with a character. Its molecule is a complex of four subunits. Thus, our hemoglobin is a protein made up of other proteins. There are two such proteins, and they are designated by the Greek letters α and β. Each hemoglobin molecule in our blood consists of two α-protein molecules (α-subunits) and two β-protein molecules (β-subunits).
In this case, all four subunits bind or release oxygen simultaneously. It is not surprising that organisms with such generous oxygen logistics have achieved a dominant position on our planet. At the same time, both α-and β-proteins are included in the extensive family of globins. Surprisingly, their closest known “relatives” in this family are not at all inclined to join in complexes and take on the modest role of subunits.
The globins are a superfamily of heme-containing globular proteins, involved in binding and/or transporting oxygen. These proteins all incorporate the globin fold, a series of eight alpha helical segments. Two prominent members include myoglobin and hemoglobin.
Most proteins are complexes of several subunits and only because of this can they perform their biological functions.
The structure of the hemoglobin is understood. However, the process of its evolution has not been explained until now. The full research is entitled, “Origin of complexity in haemoglobin evolution.”
The research focused on the fact that all globins descended from a common protein ancestor. The biologists were able to synthesize these substances and studied them in an experiment. The experiment results produced these results:
1) The mutation that produced the ANCA/β protein, which is the last common ancestor of the α and β hemoglobin proteins.
2) Two ANCA/β molecules were already able to pair with each other. The two new proteins emerged: ANCA and Ancß. These two proteins can pair.
3) ANCA and Ancß have each undergone their own mutation again. After that, the ANCA turned out to be the α-protein itself, and the Ancβ – β-protein. A pair consisting of one α-protein molecule and one β-protein molecule has the ability to combine with another such pair. Hence, it became a four-piece molecule that supplies oxygen.
Overall hemoglobin molecule consists of the four subunits that attach or give away oxygen simultaneously.
According to the research, the evolutionary lines of human and shark separated 400 million years ago. The key evolutionary breakthroughs occurred independently in the separate evolutionary lines.