Proton flux through the bacterial flagellar motor

Value 1240 protons/revolution Range: ±240 protons/revolution
Organism Bacteria Streptococcus sp.
Reference Meister M, Lowe G, Berg HC. The proton flux through the bacterial flagellar motor. Cell. 1987 Jun 5 49(5):643-50. p.646 right column 5th paragraph, p.647 right column bottom paragraph and p.648 left column top paragraphPubMed ID3034430
Method "The rotation-dependent proton flux was obtained as the difference between two measurements of the total proton flux made on the same set of cells in rapid succession. During the first measurement, the flagellar motors were rotating: in the second, they were stopped."
Comments "Each of the three experiments was performed with cells from a different culture. [Investigators] attribute the discrepancies among the above ratios of flux to speed to variability among these cultures, for example, in the mean number of motors per cell, which was not determined for each separate experiment. On average over these three studies the ratio of the rotation-dependent flux to the motor speed was (1240±240) protons per revolution." "Under the assumption of tight coupling, the ratio of proton flux to rotation rate is equal to 1240 protons per revolution and is independent of motor speed." "By calculating the corresponding torque and assuming the same ratio of proton flux to rotation rate (1240 protons per revolution), one finds a value of 0.9 for the efficiency of energy conversion."
Entered by Uri M
ID 109759