User wins Nobel Prize

John Walker, of the UK Medical Research Council's Molecular Biology Laboratory in Cambridge was the joint winner of this year's Nobel Prize for Chemistry. Dr. Walker won the prize for his studies of how hydrogen ion gradients across the membrane of a mitochondrion are used to produce ATP from its low-energy form ADP. The photo above appeared in the UK press announcing the award, and as it suggests, Dr. Walker is a regular user of IMPAX.

Dr. Walker determined the low-resolution structure of the enzyme ATP synthase, and later the atomic detail of F1, the part of the "lollipop" enzyme which sticks out of the mitochondrial membrane. These images confirmed the predictions of Paul Boyer, one of the three joint winners of this year's prize. (The third winner, who received half of the prize, was Jens Skou, whose pioneering work in the 1950s demonstrated the opposite mechanism - how ATP could be used by the cell to generate ion gradients). Boyer predicted that the gamma subunit of F1 rotates in the assembled alpha and beta subunits like a 3 cylinder motor - there are three copies each of the alpha and beta subunits. One copy of the beta subunit is bound to ADP, one to ATP, while the third is empty. As the gamma subunit rotates it pushes against one of the alpha/beta pairs, causing it to change conformation. This change in conformation apparently converts ADP to ATP.

The part of the enzyme that is imbedded in the membrane is disk shaped, and it is rotated when hydrogen ions flow through the membrane. This drives the gamma subunit, which is attached to it. The detailed structure and mechanism of the parts of the enzyme that are in the membrane are still unknown.

Dr. Walker tells us that the work for which he was awarded the prize was done before he acquired his IMPAX system, but that he uses IMPAX regularly for related projects which he is now working on.