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Photosynthesis
About: Photosynthesis is a research topic. Over the lifetime, 19789 publications have been published within this topic receiving 895197 citations.
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TL;DR: In this paper, the authors describe the characteristics of SUN and SHADE SPECIES in terms of light saturation, pigment content, and leaf anatomy, and the role of CO2 Diff usion and the carboxylation of Ribulose Diphosphate.
Abstract: INTRODUCTION 355 SUN AND SHADE SPECIES . 356 Light Saturation Characteristics 356 Pigment Content and Leaf Anatomy ..... 357 Chloroplast Structure 358 Parameters Influencing Photosynthetic Rates 359 CO2 Diff usion and the Carboxylation of Ribulose Diphosphate 360 Photosynthetic Electron Transport 361 Electron Transport Components ... 361
1,794 citations
01 Jun 1996
TL;DR: It is shown how the dynamic properties of the proteins and pigments of the chlorophyll a/b light-harvesting complexes of photosystem II first enable the level of excitation energy to be sensed via the thylakoid proton gradient and subsequently allow excessEnergy to be dissipated as heat by formation of a nonphotochemical quencher.
Abstract: When plants are exposed to light intensities in excess of those that can be utilized in photosynthetic electron transport, nonphotochemical dissipation of excitation energy is induced as a mechanism for photoprotection of photosystem II. The features of this process are reviewed, particularly with respect to the molecular mechanisms involved. It is shown how the dynamic properties of the proteins and pigments of the chlorophyll a/b light-harvesting complexes of photosystem II first enable the level of excitation energy to be sensed via the thylakoid proton gradient and subsequently allow excess energy to be dissipated as heat by formation of a nonphotochemical quencher. The nature of this quencher is discussed, together with a consideration of how the variation in capacity for energy dissipation depends on specific features of the composition of the light-harvesting system. Finally, the prospects for future progress in understanding the regulation of light harvesting are assessed.
1,786 citations
TL;DR: Observations provide compelling evidence for quantum-coherent sharing of electronic excitation across the 5-nm-wide proteins under biologically relevant conditions, suggesting that distant molecules within the photosynthetic proteins are ‘wired’ together by quantum coherence for more efficient light-harvesting in cryptophyte marine algae.
Abstract: One of the most intriguing and most studied features of photosynthesis is the exquisite efficiency with which energy can be transferred within photosynthetic complexes. A new spectroscopic study confirms earlier hints that quantum effects might be at play, by directly revealing quantum-coherent sharing of electronic excitation across 5-nm-wide photosynthetic proteins from Chroomonas CCMP270 marine algae at room temperature. The observation suggests that distant units within the proteins are 'wired' together by quantum-coherence to enhance light-harvesting efficiency. Photosynthesis makes use of sunlight to convert carbon dioxide into useful biomass and is vital for life on Earth. Crucial components for the photosynthetic process are antenna proteins, which absorb light and transmit the resultant excitation energy between molecules to a reaction centre. The efficiency of these electronic energy transfers has inspired much work on antenna proteins isolated from photosynthetic organisms to uncover the basic mechanisms at play1,2,3,4,5. Intriguingly, recent work has documented6,7,8 that light-absorbing molecules in some photosynthetic proteins capture and transfer energy according to quantum-mechanical probability laws instead of classical laws9 at temperatures up to 180 K. This contrasts with the long-held view that long-range quantum coherence between molecules cannot be sustained in complex biological systems, even at low temperatures. Here we present two-dimensional photon echo spectroscopy10,11,12,13 measurements on two evolutionarily related light-harvesting proteins isolated from marine cryptophyte algae, which reveal exceptionally long-lasting excitation oscillations with distinct correlations and anti-correlations even at ambient temperature. These observations provide compelling evidence for quantum-coherent sharing of electronic excitation across the 5-nm-wide proteins under biologically relevant conditions, suggesting that distant molecules within the photosynthetic proteins are ‘wired’ together by quantum coherence for more efficient light-harvesting in cryptophyte marine algae.
1,577 citations
TL;DR: Can PSII be exploited through increased use of biomass as an energy source and, more importantly, can the energy/CO2 problem be addressed by developing new photochemical technologies which mimic the natural system?
Abstract: Photosystem II (PSII) is the water splitting enzyme of photosynthesis. Its appearance during evolution dramatically changed the chemical composition of our planet and set in motion an unprecedented explosion in biological activity. Powered by sunlight, PSII supplies biology with the ‘hydrogen’ needed to convert carbon dioxide into organic molecules. The questions now are can we continue to exploit this photosynthetic process through increased use of biomass as an energy source and, more importantly, can we address the energy/CO2 problem by developing new photochemical technologies which mimic the natural system? (Critical review, 82 references)
1,494 citations