In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

This enzyme requires a protein from the AAA+ family for activation, and in bacteria exists as a multimer with 16 long chains and 8 short chains. It is allosterically regulated by CA1P and free phosphate groups. This enzyme requires magnesium to form an activated carbamate, and in some organisms this enzyme is sequestered in bundle sheath cells, with PEP carboxylase being used in mesophyll cells to transfer products to it. This enzyme transfers a single carbon to ribulose bisphosphate, but can react with oxygen in a side reaction called photorespiration. For 10 points, name this most abundant protein on earth, which catalyzes carbon fixation in the first step of the Calvin cycle.
Science