http://www.its.caltech.edu/~jpwilson/

Here is a little background on this paper:

Most of the carbon that is fixed on Earth is processed through the Calvin cycle. Rubisco, the carboxylating enzyme of the Calvin cycle, performs the heavy lifting. It is extremely abundant, making up ≥ 50% of the protein in most leaves, and is most concentrated within the chloroplasts.

Rubisco (full name: ‘d-ribulose-1,5-bisphosphate carboxylase/oxygenase’) has been stereotyped as a ‘bad enzyme’ for quite some time. This is because it not only acts as a carboxylase, but also as an oxygenase. Plants have a catalytic cycle that allows carbon to be fixed will regenerate the four-carbon intermediates, but if Rubisco attempts to fix O2 instead of CO2 the cycle is broken. I ... read more

Perspectives from PNAS.

Rubisco is, in fact, optimized.

A major unsolved mystery in plant hydraulics is how plants repair breaks in the transpiration stream (embolisms) when the stream is under tension. The most common model is that living cells isolate and refill empty conduits by creating a positive osmotic gradient between xylem cells and neighboring parenchyma. How this is achieved is unknown. This paper discusses how living cells come to be found in wood and what this might mean for a mechanistic understanding of embolism repair.