Ribulose-1,5-bisphosphate carboxylase/oxygenase, also known as Rubisco, is found in plants and is believed to be the most abundant protein on the planet.
Rubisco is an important enzyme used to fix carbon during photosynthesis. There are two stages in photosynthesis. Light dependent, and light independent. During Light dependent reactions, chlorophyll absorbs light and provides the electron to start the electron transport chain which eventually yields NADPH and ATP. The chlorophyll then regains the lost electron by taking one from water producing oxygen as a product. During light independent reactions, Rubisco takes up CO2 from the atmosphere and undergoes the Calvin Cycle to produce 3-carbon sugars used to make glucose.1

A summery of glucose synthesis in plants via the light dependent and like independent pathways

Image courtesy of: http://trc.ucdavis.edu/biosci10v/bis10v/week3/2stage.gif

The calvin cycle, a glucose synthesis pathway in the light independent reactions in which Rubisco is a main participant  Image courtesy of: http://courses.cm.utexas.edu/emarcotte/ch339k/fall2005/Lecture-Ch19-3/SlideCalvinCycle.jpg

There are many reasons why Rubisco is model protein for isolating in lab. First, because of its inefficiency as an enzyme, plants produce Rubisco in large amounts, making it relatively easy to isolate. Secondly, it is found pretty much universally among many species, thus it can be treated the same way experimentally between species. Thirdly, it is a very well studied protein thus there is much information known about the protein and its behavior in plants. 2.

This experiment focuses on the role of Rubisco in Dieffenbachia Camille a plant found in tropical environments.

Dieffenbachia Camille in its natural habitat Image courtesy of:
http://aoki2.si.gunma-u.ac.jp/BotanicalGarden/PICTs/dieffenbachia-amoena.jpeg

Previous research had supported the hypothesis that Rubisco levels differ from plant leaves in a high concentration of light than in low. 3Since this information tied rubisco to chlorophyll and the light source, and chlorophyll is known to give leaves their green pigment, this experiment now set out to discover the difference of Rubisco levels in different pigmentation of the leaf. Our hypothesis was that the white areas of the leaf will have noticeably less Rubisco than the green areas.  The white region of the leaf lack chlorophyll or have malfunctioning chlorophyll that results in lack of pigmentation. It is suspected that to this non functioning chlorophyll might have other genetic implications in the cell such as down regulation of other photosynthetic proteins, such as rubisco.

References
1. http://en.wikipedia.org/wiki/Photosynthesis
2. http://web.mit.edu/esgbio/www/ps/dark.html
3. http://pcp.oxfordjournals.org/cgi/content/abstract/30/2/221