Word: stoeckenius
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...employ a natural converter to get energy directly from sunlight. Last week Cell Biologist Walther Stoeckenius, 54, with colleagues at the University of California at San Francisco and a team from NASA'S Ames Research Center, announced that a purple pigment found in red bacteria from the Dead Sea and salt flats round the world also directly converts sunlight into energy. While the pigment is less efficient than chlorophyll-only an estimated 10% of light energy is converted-it is more stable and easily extracted from the bacteria...
Visual Purple. Stoeckenius began the work that led to his discovery in 1965 while serving as an associate professor at New York City's Rockefeller University. Studying the structure of a microbe called Halobacterium halobium -the organism that gives red herring their distinctive color-he found a purple pigment that was chemically similar to "visual purple," a pigment in the retinas of animal and human eyes. The similarity led Stoeckenius and his co-workers to suspect that the pigment helped the organism use light for its life processes...
Continuing his research after transferring to California in 1967, Stoeckenius found that the pigment, called bacteriorhodopsin, functioned as a sort of pump, converting sunlight directly into electrochemical energy. Light striking a pigment molecule causes it to eject a hydrogen ion-or proton-that passes through the cell's membrane. The movement of the positively charged protons through the membrane leaves an excess of negative charge on one side of the membrane. That produces a voltage gradient and results in an electrical current flowing through the membrane. In the process, which involves at least five separate steps, each bacteriorhodopsin molecule...
...Stoeckenius reported that researchers are already experimenting with bacteriorhodopsin in efforts to build a photoelectric cell. Stoeckenius also believes bacteriorhodopsin's chemical similarity to visual purple could help scientists better understand the basic processes of vision and could offer new insights into cell biology. "All living cells need to pump ions across their cell membranes," says Stoeckenius. "It seems to me that we are close to discovering certain basic cellular functions...
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