"Rubisco is like a blobby doughnut (round with a small hole in the middle) made out of eight separate protein chains and is unusual in being a soluble enzyme that has only extremely recently been successfully re- folded in a test tube. This tells us that the structure of Rubisco needs to be extremely precise in order for it to work. (Most other soluble enzymes can be treated a lot more roughly and are generally easy to manipulate.) "