T_cSUH Bi-Weekly Seminars

Friday, July 24, 2009

12:00 PM - 01:00 PM

Rotary motors, including ATP synthase, V-type ATPases, and the bacterial flagellar motor, play crucial roles in living organisms. In humans and other eukaryotes, ATP synthase operates in the inner membranes of mitochondria to produce adenosine triphosphate (ATP), life’s chemical currency of energy. V-type ATPases utilize the energy of ATP hydrolysis to create electrochemical potential differences (usually of protons) across diverse biological membranes. I will describe our recently proposed electric field driven torque model of ion-driven rotary motors. The model predicts a scaling law relating torque to the number of ion-carrying subunits in the rotor, the number of stators, and the ion motive force across the membrane. When the FO complex of ATP synthase is coupled to F1, the model predicts a minimum proton motive force (pmf) needed to drive ATP production by F1. By contrast the model predicts a maximum pmf against which the V1 complex of a V-type ATPase can overcome the opposing torque by V0 to pump protons back across the membrane. We are also working to develop label-free electromagnetic sensors to detect activity and possible dysfunction of mitochondrial and other enzymes. Dysfunction of mitochondrial enzymes has been implicated in type-2 diabetes, cancer, heart disease, and neurodegenerative diseases, while dysfunction of V-type ATPases has been implicated in osteopetrosis, distal renal tubular acidosis, and many other diseases. Therefore, improved understanding of such enzymes is broadly significant to human health.