Calvin Cycle.... RuBP carboxylase?!?

Question

The enzyme responsible for fixing carbon dioxide in the first step of the Calvin cycle is RuBP carboxylase. This is said to be the most plentiful protein in plants. Some say it is the most plentiful in the world. Is there any significance to this claim? Explain

Answer 1

Yes, this is all quite true.  RuBP carboxylase is a rather slow enzyme while also being much larger than the average protein molecule.  So the leaf must make quite a lot of it to compensate for this slow turnover while maintaining adequate rates of photosynthesis.  Since all plants make this enzyme it can be legitimately claimed to the most abundant protein in the world.