| Value |
164
kJ/mol electron moved
Range: 110 kJ/mol + (3×18 kJ/mol) kJ/mol electron moved
|
| Organism |
Unspecified |
| Reference |
John A. Raven Functional evolution of photochemical energy transformations in oxygen-producing organisms, Functional Plant Biology, 2009, 36, 505–515 p.512 left column 4th paragraph |
| Primary Source |
Raven JA (1984) ‘Energetics and transport in aquatic plants.’ (A. R. Liss: New York) |
| Comments |
Comparing the operating costs of oxygenic photosynthesis,
moving one electron from water to NADP+ with the coupled
pumping of three protons across the photosynthetic membrane
takes at least two absorbed photons given the relatively low
photon yield of PSII. The energy stored in the products listed
in the last sentence is 110 kJ + (3×18 kJ) or 164 kJ per mol
electron moved (Raven 1984b). One mol 680 nm photon
(PSII) contributes 176 kJ and one mol 700 nm photon (PS1)
contributes 171 kJ, a total of 347 kJ. Even with 100%
photochemical efficiency of both photosystems the overall
efficiency of energy capture is 164/347 (i.e. 47%)
(Table link, BNID 105061). For the mean wavelength of photosynthetically
active radiation (i.e. 550 nm), the efficiency is 163/(2×218)
or 37%. For an ion-pumping rhodopsin with an absorption
maximum at 550 nm, the energy input is 218 kJ per mL
photon. As the energy stored in the movement of a single mol
of protons is only 18 kJ, BNID 105062, the efficiency is only 8% BNID 105056 (Table link). |
| Entered by |
Uri M |
| ID |
105060 |