RuBisCO - RuBisCO Vs Alternative Carbon Fixation Pathways

RuBisCO Vs Alternative Carbon Fixation Pathways

RuBisCO is important biologically because it catalyzes the primary chemical reaction by which inorganic carbon enters the biosphere. Many autotrophic bacteria and archaea fix carbon via the reductive acetyl CoA pathway, the 3-hydroxypropionate cycle, or the reverse Krebs cycle. These pathways are relatively smaller contributors to global carbon fixation than that catalyzed by RuBisCO. Phosphoenolpyruvate carboxylase, PEPC, only temporarily fixes carbon. Reflecting its importance, RuBisCO is the most abundant protein in leaves, accounting for 50% of soluble leaf protein in C₃ plants (20–30% of total leaf nitrogen) and 30% of soluble leaf protein in C₄ plants (5–9% of total leaf nitrogen). Given its important role in the biosphere, the genetic engineering of RuBisCO in crops is of continuing interest (see below).