NCSA NEWS

ATP is the principal energy carrier in living cells. It is often synthesized from ADP and inorganic phosphate using a transmembrane proton gradient that is maintained by food molecule oxidation in animals or photosynthesis in plants and some bacteria. Energy released by the hydrolysis of ATP drives a number of vital biochemical reactions, including enzymatic catalysis and mechanical movements. These visualizations of an ATP molecule in its binding site highlight two subunits of the F1 unit of an enzyme known as F0-F1 ATP-synthase. The alpha subunit is shown in yellow, the beta subunit in blue. (The image at right shows the whole enzyme, the top image zooms in on the binding site.) The enzyme uses the mechanical force generated by the rotation of its transmembrane unit, F0, to catalyze ATP synthesis in the catalytic F1 unit. These units interact mechanically through the central stalk, shown in red. A full atomic-level model of the F1 unit in an aqueous environment was recently created by Barry Isralewitz, Klaus Schulten, and Emad Tajkhorshid of the Theoretical Biophysics Group at the University of Illinois. The simulation included 327,000 atoms, captured one nanosecond of the unit's molecular dynamics, and required 10 days of computing time on the Alliance's 256-processor Origin2000 supercomputer at NCSA. Schulten's group has since ported his code to NCSA's Linux clusters and has had achieved excellent performance on both the IA-32 and IA-64 clusters. Access Online | Posted 10-9-2001