When sunlight strikes a photosynthesizing organism, energy flashes between proteins just beneath its surface until it is trapped as separated electric charges. Improbable as it may seem these tiny hits of energy eventually power the growth and movement of all plants and animals. They are literally the sparks of life.
The three clumps of protein a light-harvesting antenna called a phycobilisome and photosystems I and II look like random scrawls in illustrations but this is misleading. They are able to do their job only because they are positioned with exquisite precision.
If the distances between proteins were too great or the transfers too slow, the energy would be wasted and ultimately all entropy-defying assemblages like plants and animals would fall to dust.
But until now scientists weren't even sure the three complex cohered as a single sun-worshipping megacomplex. Previous attempts to isolated connected complexes failed because the weak links that held them together broke and the megacomplex fell apart.
In the Nov. 29 issue of Science scientists at Washington University in St. Louis report on a new technique that finally allows the megacomplex to be plucked out entire and examined as a functioning whole.
Like a seamstress basting together the pieces of a dress, the scientists chemically linked the proteins in the megacomplex. Stabilized by the stitches, or crosslinks, it was isolated in its complete, fully functional form and subjected to the full armamentarium of their state-of-the-art labs, including tandem mass spectrometers and ultra-fast lasers.
The work was done at PARC (Photosynthetic Antenna Research Center), an Energy Frontier Research Center funded by the Department of Energy that is focused on the scientific groundwork needed to maximize photosynthetic efficiency in living organisms and to design biohybrid or synthetic ones to drive chemical processes or generate photocurrent.
|Contact: Diana Lutz|
Washington University in St. Louis