2-Phosphoglycolate

2-Phosphoglycolate (chemical formula C2H2O6P3-; also known as phosphoglycolate, 2-PG, or PG) is a natural metabolic product of the oxygenase reaction mediated by the enzyme ribulose 1,5-bisphosphate carboxylase (RuBisCo).

In a process called photorespiration RuBisCo can also catalyze addition of atmospheric oxygen to the C2 carbon of RuBP forming a high energy hydroperoxide intermediate that decomposes into 2-phosphoglycolate and 3-phosphoglycerate.

[3] The activities of important enzymes in the central carbon metabolism of the chloroplast such as triose-phosphate isomerase, phosphofructokinase, or sedoheptulose 1,7-bisphosphate phosphatase show a significant decrease in the presence of 2-PG.

A decrease in the oxygenation of RuBP may result in a boost in the efficiency of carbon assimilation in crops such as rice or wheat and therefore increase their net biomass production.

Mutations in the L-subunit of the enzyme, for example, have been shown to increase both the catalytic turnover rate and RuBisCos affinity for carbon dioxide[7]

Photorespiration serves as a salvage pathway that converts 2-PG into non-toxic metabolites. Contrary to the Calvin cycle, this pathway is responsible a net loss of previously fixed carbon. It also serves as sink for ATP and NADH.