Proton flux through each channel of flagellar motor

Value 19400 H+/sec
Organism Bacteria Escherichia coli
Reference Gabel CV, Berg HC. The speed of the flagellar rotary motor of Escherichia coli varies linearly with protonmotive force. Proc Natl Acad Sci U S A. 2003 Jul 22 100(15):8748-51. p.8751 left columnPubMed ID12857945
Method "...[assuming] tight coupling, the speed–pmf relation measured here demonstrates a simple ohmic current–pmf relation, also indicative of such channels. If (i) two protons are used per mechanical step of a single torque generating unit (ref 1), (ii) each one travels through a separate channel (ref 14), (iii) there are ˜50 such steps per revolution (rev) (ref 15), and (iv) the motor spins at 380Hz at zero load (ref 3), then the flux through each channel is ˜50H+/rev × 380Hz=1.9×10^4H+/s."
Comments "This result is about the same as the current through an open, ˜30-fS voltage-gated proton channel (ref 13): 4.5 fA (at 150mV)  ˜2.8?10^4H+/s. Both of these fluxes are much smaller than those observed in other ion channels."
Entered by Uri M
ID 109822