Ribulose bisphosphate carboxylase/oxygenase ( Rubisco ) is a key enzyme in photosynthesis catalyzing corbon dioxide fixation. Rubisco is ubiquitus for photosynthetic organisms and is regarded as the most abundant protein on earth. More than 90% of the inorganic carbon that is converted into biomass is fixed by the enzyme RubisCO that catalyzes the carboxylation and cleavage of ribulose-1,5-bisphosphate (RuBP) into two molecules of 3-phosphoglycerate (3PG). RubisCO is found in all three domains of life: bacteria, archaea and eukaryotes. The enzyme makes up 30-50% of the soluble protein in plant leaf. Structure Rubisco enzymes are multimeric having two different types of subunits catalytic large (L, 50–55 kDa), and small (S, 12–18 kDa) subunits. Different molecular forms of Rubisco are distinguished by the presence or absence of the small subunit. The most common form (form I) of Rubisco is composed of large and small subunits in a hexadecameric structure, L8S8. This form is presen...
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