fotorespirációban

Fotorespirációban, often translated as photorespiration, is a metabolic pathway that occurs in plants, algae, and cyanobacteria. It is a process that consumes oxygen and releases carbon dioxide, seemingly counteracting photosynthesis. This process is initiated when the enzyme RuBisCO, which is responsible for carbon fixation in photosynthesis, binds with oxygen instead of carbon dioxide. This binding leads to the formation of phosphoglycolate, a toxic byproduct.

The photorespiratory pathway then proceeds to metabolize phosphoglycolate, converting it into glycerate, which can then re-enter the Calvin cycle. This conversion requires energy in the form of ATP and reducing power in the form of NADPH. While photorespiration leads to a net loss of fixed carbon and energy, it is thought to play several important roles.

One proposed function is to protect plants from photooxidative damage under conditions of high light intensity and low CO2 availability, such as during drought or high temperatures. By consuming excess ATP and reducing power generated during photosynthesis, photorespiration can prevent the buildup of reactive oxygen species. Another potential role is in nitrogen metabolism, as intermediates of the photorespiratory pathway are involved in amino acid synthesis. The efficiency of photorespiration varies depending on plant species and environmental conditions. Plants adapted to hot, dry climates, such as C4 plants, have evolved mechanisms to minimize photorespiration by concentrating CO2 around RuBisCO.