Energy in photosynthesis

Duysens, L.N.M. Transfer of excitation energy in photosynthesis. Thesis, Utrecht 1952... 

Magnesium has its role intimately intertwined with phosphate in many phosphoryl transfer reactions, as Mg-ATP in muscle contraction, in the stabilization of nucleic acid structures as well as in the catalytic activity of ribozymes (catalytic RNA molecules). It also serves as a structural component of enzymes, and is found as the metal centre in chlorophylls, which absorbs light energy in photosynthesis. 

CYTOCHROME b-559 AS A TRANSDUCER OF REDOX ENERGY INTO ACID-BASE ENERGY IN PHOTOSYNTHESIS... 

In 1944, Emerson, Stauffer, and Umbreit proposed that the function of light energy in photosynthesis is the formation of energy-rich phosphate bonds (p. 107). In their model (hereafter, the Emerson model ), the free energy necessary to drive both C02 fixation and reduction came from these energy-rich phosphate bonds (i.e., ATP), produced as a result of light absorption by a chlorophyll-containing protein. 

Proton-coupled electron transfer (PCET) reactions play a vital role in a wide range of chemical and biological processes. For example, PCET is required for the conversion of energy in photosynthesis [1] and respiration [2], In particular, the coupling between proton motion and electron transfer is involved in the pumping of protons across biological membranes in photosynthetic reaction centers [1] and in the conduction of electrons in cytochrome c [3]. In addition to biological processes, PCET is also important in electrochemical processes [4, 5] and in solid state materials [6]. 

LNM Duysens (1952) Transfer of excitation energy in photosynthesis. Utrecht University dissertation RK Ciayton (1965) The biophysical problems of photosynthesis. Science 149 1246-1254 WW Parson (1978) The bacterial reaction center, in J Amesz (ed) Photosynthesis, pp 43-61. Eisevier R4. G Feher (1992) Identification and characterization of the primary donor in bacterial photosynthesis a chronological account of an EPR/ENDOR Investigation (The Bruker Lecture). J Chem Soc Perkin Transactions 2 1861-1874... 

The primary conversion of light energy into chemical redox energy in photosynthesis can therefore be described by a simple scheme [Kok (111)] ... 

Fig. 5. Simplified scheme of the conversion of light energy into redox energy in photosynthesis (KOK 111).

Duysens LNM (1952) Transfer of excitation energy in photosynthesis. Doctoral thesis. State University at Utrecht, Drukkerij en uitgevers-maatschappij v/h Kemink en zoon NV, Domplein 2, Utrecht... 

Absorption of light by a molecule excites it from the ground state to a higher electronic state. With photosynthetic pigments, the excited electron occupies a IT orbital in the system of conjugated double bonds of the porphyrin. The excitation energy in photosynthesis is harvested in two ways ... 

Plants utilize solar energy in photosynthesis, the reaction in which the energy of sunlight is used to convert CO2 and H2O into carbohydrates and O2. One common photosynthetic reaction produces the sugar glucose ... 

ChlOfOphyll A plant pigment that plays a major role in conversion of solar energy to chemical energy in photosynthesis. (Section 23.3)... 

Fig. 1. Possible fates of absorbed energy in photosynthesis (Modified from Krause,...

Young, A.J., Phillip, D., Ruban, A.V., Horton, P., Frank, H.A. The xanthophyll cycle and carotenoid-mediated dissipation of excess excitation energy in photosynthesis. Pure Appl. Chem. 69, 2125-2130 (1997)... 

D. I. Arnon, Conversion of light into chemical energy in photosynthesis, Nature, 184, 10-21 (1959). 

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