Research: Project 4

Using stable isotopes to study metabolic  processes.

Isotopes_Metabolic water-2Stable isotopes are commonly used to probe complex biological and environmental processes. In particular, hydrogen, carbon, nitrogen, and oxygen isotopes can help dissect enzymatic reaction mechanisms and can be employed as tracers to follow metabolic pathways. For example, the molecular intersection of oxygen and hydrogen atoms in essentially all biological processes is intracellular water, a product of both aerobic and anaerobic metabolism as well as a biosynthetic substrate. Despite the universal recognition of O and H fluxes as part of metabolic activity, these fluxes remain largely uncharacterized, and we have pioneered this field of study using isotope-ratio mass spectrometry and laser spectroscopy as our primary tool.

Isotope-ratio mass spectrometry has also been instrumental in our ability to dissect microbial H2 metabolism. Because different hydrogenases have slightly different preferences for the light versus the heavy isotope, each will generate H2 with a unique isotopic signature that can be used to monitor individual enzyme activity.

Isotopes_N2O-2Similarly, the potent greenhouse gas N2O also has different nitrogen and oxygen isotope values depending on its source. By defining the unique isotopic signature of different N2O producing enzymes, we are improving our understanding of the atmospheric N2O flux.