Brussels, 06 Apr 2006
Finnish researchers have cracked one of the most enduring puzzles of biochemistry - how cells 'breathe', or more correctly, respire. The team from the University of Helsinki has identified an electron transfer mechanism which powers a 'proton pump'.
We rely on oxygen to live. Oxygen enters the lungs and attaches itself chemically to red blood cells, which are then taken around the body. The team identified the enzyme cytochrome oxidase as the conduit enabling the energy held in the oxygen to be transferred through the cell membrane and into the cell. It then drives a second mechanism to produce ATP, which is the cell's internal staple energy, and other biological machines.
Professor Mårten Wikström's team found that the reduction (electron gain) of the oxygen powered a 'proton pump' across the cell membrane. The protons cross the cell membrane, driving the biochemical activities within the cell. The exchange of electrons required to couple oxygen and hydrogen atoms to make water is what drives this process. 'This finding opens the door towards understanding the mechanism, which has been the subject of research for almost 30 years,' he said.
The process has been likened to a biological nanomachine of very high efficiency. As the positively charged molecules are leaving the cell, this creates an 'electrochemical proton gradient', which is something like a battery, driven by the cell membrane itself.
The team discovered that the reduction of the oxygen takes place via an iron site known as haem a. The team found for the first time that the haem a site and the proton pump are kinetically linked - the one drives the other, enabling the cell to breathe.