stoichiometry of the number of protons required to be transferred for each
ATP synthesized remains an open question. A full rotation of the enzyme
should lead to the synthesis of three molecules of ATP. If we assume that
each csubunit translocates oneproton per cycle, then the H+/ATP ratio is
given by the number of csubunits divided by three. However, the number
of protons is related to the rotation of the cring but the number of csub-
units in the F 0 domain is not the same for enzymes isolated from differ-
ent organisms. For an enzyme with 12 csubunits, the ratio is 12H+/3ATP
or 4H+/ATP. With a range of 10 –14 for the number of csubunits, the cal-
culated ratio is 4.67:3.33 H+/ATP. Whereas an integer value for H+/ATP
would make life simple as the gearing is direct, the ratio may be a non-
integer due to nonlinear responses which have not yet been identified.
CHAPTER 6 REDOX REACTIONS AND BIOENERGETICS 131
References
Abrahams, J.P., Leslie, A.G.W., Lutter, R., and
Walker, J.E. (1994) Structure at 2.8 Å resolution
of F 1 -ATPase from bovine heart mitochondria.
Nature 370 , 621– 8.
Berry, E.A. and Huang, L. (2003) Observations con-
cerning the quinol oxidation site of the cytochrome
bc 1 complex. FEBS Letters 555 , 13 –20.
Boyer, P.D. (2000) Catalytic site forms and controls
in ATP synthase catalysis. Biochimica Biophysica Acta
1438 , 252– 62.
Crofts, A.R. and Berry, E.A. (1998) Structure and
function of the cytochrome bc 1 complex of mito-
chondria and photosynthetic bacteria. Current
Opinions in Structural Biology 8 , 501–9.
Darrouzet, E., Moser, C.C., Dutton, P.L., and Daldal,
F. (2001) Large scale domain movement in cyto-
chrome bc 1 : a new device for electron transfer
in proteins. Trends in Biochemical Sciences 26 ,
445 –51.
Iverson, T.M., Luna-Chavez, C., Cecchini, G., and
Rees, D.C. (1999) Structure of theEscherichia coli
fumerate reductase respiratory complex. Science
284 , 1961– 6.
Iwata, S., Lee, J.W., Okada, K. et al. (1998) Complete
structure of the 11-subunit bovine mitrochondrial
cytochrome bc 1 complex. Science 281 , 64 –71.
Jagendorf, A.T. (1998) Chance, luck, and photo-
synthesis research: an inside story. Photosynthesis
Research 57 , 217–29.
Junge, W. and Nelson, N. (2005) Nature’s rotary elec-
tromotors. Science 308 , 642– 4.
Kinosita, K., Adachi, K., and Itoh, H. (2004) Rota-
tion of F1-ATPase: how an atp-driven molecular
machine may work. Annual Re 9 iew of Biophysics
and Biomolecular Structure 33 , 245 – 68.
Lancaster, C.R.D., Kröger, A., Auer, M., and Michel,
H. (1999) Structure of fumerate reductase from
Wolinella succinogenesat 2.2 Å resolution. Nature 402 ,
377– 85.
Lange, C. and Hunte, C. (2002) Crystal structure of
the yeast cytochrome bc 1 complex with its bound
substrate cytochrome c. Proceedings of the National
Academy of Sciences USA 99 , 2800 –5.
Meier, T., Polzer, P., Diederichs, K., Welte, W., and
Dimroth, P. (2005) Structure of the rotot ring of
F-type Na+-ATPase from Iyobacter tartaricus. Science
308 , 659 – 62.
Murata, T., Yamato, I., Kakinuma, Y., Leslie, A.G.W.,
and Walker, J.E. (2005) Structure of the rotor of the
V-type Na+-ATPase from Enterococcus hirae. Science
308 , 654 –9.
Sarasta, M. (1999) Oxidative phosphorylation at the
fin de siecle. Science 283 , 1488 –93.
Sazanov, L.A. and Hinchiffe, P. (2006) Structure of
the hydrophilic domain of respiratory complex I
from Thermus thermophilus. Science 311 , 1430 – 6.
Xia, D., Yu, C.A., Kim, H. et al. (1997) Crystal struc-
ture of the cytochrome bc 1 complex from bovine
heart mitochondria. Science 277 , 60 – 6.
Yankovskaya, V., Horsefield, R., Tornroth, S. et al.
(2003) Architecture of succinate dehydrogenase and
reactive oxygen species generation. Science 299 ,
700 – 4.
Zhang, Z., Huang, L., Schumleister, V.M. et al.
(1998) Electron transfer by domain movement in
cytochrome bc 1. Nature 392 , 677– 84.