Laboratory of Photobiology
Dr. Mauzerall’s research focuses on the photochemistry, origin and evolution of photosynthesis and vision. His lab developed photoacoustic methods to determine enthalpy and volume changes of individual photoreaction steps in these processes. These methods allow a very simple and rapid measure of the efficiency of the process. By quantifying the electrostriction on initial charge separation and the thermodynamic efficiency of photosynthetic systems, along with the enthalpy and volume changes in the photocycle of the proton pump bacteriorhodopsin, Dr. Mauzerall’s lab has found that, unlike simple reaction systems, those of photobiology can contain a large entropy component. Certain steps in photosystem I during photosynthesis and in bacteriorhodopsin are driven by entropy. His lab is now extending these measurements to the thermodynamics of the all-important oxygen-forming system of photosynthesis. Preliminary results show that the enthalpy is constant in the four electron transfer steps required to form oxygen from water, indicating that evolution has not only solved the problem of “splitting” water but has succeeded in developing the minimum energy path for the formation of oxygen. The understanding of this system is crucial to the use of photosynthesis as a source of energy. Dr. Mauzerall is also determining the efficiency of a unique cyanobacterium that uses chlorophyll d, which absorbs at longer wavelengths than the usual chlorophyll a. He finds the efficiency at the wavelength of light absorbed by chlorophyll d is at least equal to, if not more than, that in chlorophyll a organisms. The results indicate that the long wavelength limit to the photosynthetic formation of oxygen has not yet been reached, a finding that would be of interest to astrobiologists studying the possibility of life-supporting planets located near stars that are substantially more red than the sun.
A third project in Dr. Mauzerall’s lab examines the formation of hydrogen from ferrous ion at a neutral pH as a source of required reducing agents for the origin of life. The atmosphere of the early Earth is now estimated to have been largely nitrogen and carbon dioxide, not ammonia and methane. The highly reducing conditions would have allowed for the formation of amino acids and the bases for nucleotides, but the more neutral conditions present a problem for the chemical evolution of life. Dr. Mauzerall’s research has found that ferrous ion, abundantly present in the Archaen Ocean, readily forms hydrogen at a neutral pH, both thermally and photochemically. It is thus a good source of reducing power for the reduction of nitrogen and carbon dioxide to the molecules required for the origin of life. His lab is now trying to reduce nitrogen to ammonia with this reaction.
Dr. Mauzerall received his B.S. in chemistry from Saint Michael’s College in 1951 and his Ph.D. in organic chemistry from the University of Chicago in 1954. He joined Rockefeller in 1954 as a research associate. He became assistant professor in 1959, associate professor in 1964, professor in 1969 and professor emeritus in 2001. He is a member of the American Association for the Advancement of Science.