Sandbox Reserved 494: Difference between revisions

ATP synthesis is the most prevalent chemical reaction in the biological world and ATP synthase is one of the most ubiquitous, abuntant proteins on earth. From '''<FONT COLOR="#E42217">''Escherichia coli''</FONT>''' to plants and mammals, this enzyme is one of the most conserved during evolution<ref name="PP"> PMID: 11533724</ref>. PDB code of ATP synthase is [[1c17]]. The molecular study of ATP synthase was initiated in 1960 when Efraim Racker and his colleagues reported the isolation of soluable factor from beef heart mitochondria. ATP synthase produces ATP from '''<FONT COLOR="#E42217"> '''adenosine diphosphate </FONT> (ADP) and inorganic phosphate with the use of energy from a transmembrane proton-motive force generated by respiration or photosynthase<ref>PMID: 10576729</ref>.

The energy for ATP synthesis is provided from proton transport along the gradient of electrochemical potential of protons across membranes (△H). When the magnitude of △H is large, as in functional mitochondrial, downhill proton flow through F₀ causes rotation of the F₀ rotor and hence rotation of the γε-subunits of F₁. The rotary motion of the γ alternates the structure of the β-subunit so the ATP is synthesized<ref>PMID: 12788493</ref>. Mutagenesis of catalyticsites of ATP synthase have proceeded extensively in the ''E. coli'' enzymes, somewhat less so in '''<FONT COLOR="#571B7e">''Saccharomyces cerevisiae''</FONT>''' and '''<FONT COLOR="#F535AA">''Bacillus'' PS3</FONT>''', and to far lesser extent in other species. Almost without exception, detailed in vitro biochemical analyses of purified mutant enzymes have been limited to the ATP hydrolysis reaction. However, in both yeast and E. coli, growth tests on nonfermentable substrates provide sensitive if quantative assays of ATP synthesis in the cell. Ligands to the Mg²⁺ cation have been studied in detail by mutagenesis and functional analysis <ref>PMID: 9425083 </ref>.

As a motor protein, ATP synthase offers a rare research opportunity. Structure of the F₁ motor, both rotor and stator in the same assembly, are known in atomic detail for the first time, and rotation can be analyzed at sub-millisecond time resolution <ref>PMID: 10840052</ref>. An emerging possibility of step-size mismatch between the F₁ and F₀ motors provides an opportunity to find a noval coupling mechanism of the two motors that will explain why the mismatch is good for the enzyme. Finally, one can even dream of using this, the world's tiniest motor, as an engine part in the fabrication of nano-machines. The marvel of ATP will continue<ref name="PP"/>.