Paul D. Boyer and John E. Walker have shown how the enzyme ATP synthase makes ATP. ATP synthase is found in chloroplast and mitochondrial membranes and in the cytoplasmic membrane of bacteria. A difference in hydrogen ion concentration across the membrane drives the enzyme to synthesise ATP.
"The Binding Change Mechanism"
Using chemical methods Paul Boyer proposed that ATP synthase is like a cylinder with alternating alpha and beta subunits. An asymmetrical gamma subunit in the middle of the cylinder causes changes in the structure of the beta subunits when it rotates (100 r.p.s.). He termed these structures open (betaO), loose (betaL) and tight (betaT).
Four stages in ATP
A molecular machine is discovered
John Walker crystallised the enzyme to study its details. He established that Boyer's proposal for how ATP synthesis takes place, the "molecular machine", was correct.
The enzyme consists of an
FO part bound in the membrane and a
projecting F1 part. The F1 part
is known in detail, while less is known about the