Protein involved in photosynthesis, the process in which light energy is absorbed by photosynthetic pigments (e.g. chlorophyll) and converted to chemical energy (usually ATP and NADPH, =light reaction). This energy is subsequently used as an energy source for the reduction of carbon dioxide to carbohydrate (=Calvin cycle). The general reaction is: CO(2) + 2H(2)A = (CH(2)O) + 2A + H(2)O, where 2H(2)A is any reduced compound that can serve as an electron donor. In plants, algae and cyanobacteria H(2)O serves as a reductant, generating O(2). Non-oxygenic organisms use other electron donors, for example H(2)S in purple sulfur bacteria, generating sulfur.

› Biological process

› photosynthesis [ GO:0015979 ]