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Photosynthesis: Energy Conversion

  1. Gözde Ulas,
  2. Gary W. Brudvig

Published Online: 15 DEC 2011

DOI: 10.1002/9781119951438.eibc0455

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Ulas, G. and Brudvig, G. W. 2011. Photosynthesis: Energy Conversion. Encyclopedia of Inorganic and Bioinorganic Chemistry. .

Author Information

  1. Yale University, New Haven, CT, USA

Publication History

  1. Published Online: 15 DEC 2011

Abstract

The process of water oxidation and carbon dioxide reduction in oxygenic photosynthesis involves a complex series of events that start with light energy capture and end with its storage in the form of the chemical energy in glucose. These reactions provide a solution to efficient solar energy conversion into high-energy chemicals. The principles revealed by study of natural photosynthetic systems may be used to design artificial systems for solar fuel production. Understanding the light-driven oxidation of water, in particular, is of high interest, as this half reaction could be used in sustainable solar fuel production by processes of artificial photosynthesis to meet the world's growing energy demand. In this article, we look into the intricate photosynthetic machinery and the various processes that it performs in order to efficiently capture, convert, and store light energy. Our main focus is on the so-called “light” reactions, where specific processes are driven by direct light absorption. As a result, reducing equivalents are extracted from water and transferred to NADP+, to be used in the carbon-fixing reactions, which are not directly modulated by sunlight. We describe the characteristic features of each protein in the photosynthetic electron-transport machinery, and specifically focus on the water-oxidation catalysis performed as the first step of oxygenic photosynthesis by the metalloenzyme photosystem II, due to its relevance to synthetic biomimetic water-oxidation catalysts. Several processes that photosystem II employs to couple light energy absorption to catalytic turnover are discussed, including proton and electron transfers, redox leveling, charge accumulation, and proposed catalytic mechanisms.

Keywords:

  • light energy conversion;
  • oxygen-evolving complex;
  • photosynthesis;
  • photosystem I;
  • photosystem II;
  • solar energy;
  • water oxidation