from the Natural-Nanomachines dept.
According to a press release (7 March 2002), a molecular pump that helps cells produce chemical energy has been visualised by scientists at Imperial College, London. The structure of the pump, a key enzyme in bacterial respiration, reveals the molecular mechanisms that underpins cellular respiration, and confirms a Nobel Prize-winning theory proposed over 40 years ago by Peter Mitchell. Professor So Iwata and colleagues from the Laboratory of Membrane Protein Crystallography, Imperial College Centre for Structural Biology described their study of the structure of the enzyme formate dehydrogenase-N looks at a resolution of 1.6 angstroms in the 7 March 2002 issue of Science.
Their work with the bacteria E. coli provides the first real evidence for the 'chemiosmotic' theory proposed by Dr Peter Mitchell in 1961. Initially dismissed by mainstream science, Mitchell's theory on energy conversion is now accepted as a fundamental principle in the field of bioenergetics, the process by which living cells release energy in a controlled and useable form by converting metabolic energy derived from respiration into a compound called adenosine triphosphate (ATP). "In all cells, metabolites are converted via a series of respiratory enzymes into an electric potential or 'proton motive force' across the cell membrane. This proton motive force drives the generation of ATP," said Professor Iwata.
Professor Iwata and his team are the first to solve the structure of a respiratory enzyme that produces the proton motive force by the "redox-loop mechanism" originally proposed by Peter Mitchell. "Forty years on, this is the first enzyme structure to be determined that shows Peter Mitchell's original hypothesis of how cells convert energy into a usable form is correct," said Professor Iwata.