Methanotrophic bacteria (or "methanotrophs") oxidize methane and convert it to methanol. In doing so, not only are they removing a dangerous greenhouse gas from the environment, they are also creating a sustainable fuel.
A complex conversion
For years, however, scientists have been unable to figure out how these bacteria perform this complex conversion. Now, an interdisciplinary team at Northwestern University Scient may have uncovered this long-held mystery.
Their finding could lead to human-made catalysts that can convert methane to readily usable and sustainable methanol. The discovery indicates that the enzyme responsible for the methane-methanol conversion catalyzes this reaction at a site that contains just one copper ion.
"The identity and structure of the metal ions responsible for catalysis have remained elusive for decades," said Northwestern's Amy C. Rosenzweig, co-senior author of the study and the Weinberg Family Distinguished Professor of Life Sciences in Northwestern's Weinberg College of Arts and Sciences.
"Our study provides a major leap forward in understanding how bacteria methane-to-methanol conversion."
"By identifying the type of copper center involved, we have laid the foundation for determining how nature carries out one of its most challenging reactions," said Brian M. Hoffman, co-senior author and Charles E. and Emma H. Morrison Professor of Chemistry at Weinberg.
Crucial to understand
Today's industrial processes to catalyze a methane-to-methanol reaction require extreme conditions such as tremendous pressure and temperatures reaching higher than 1,300 degrees Celsius. Methanotrophs, however, can effortlessly perform the reaction at room temperature. This is why their process is so crucial to understand.
"While copper sites are known to catalyze methane-to-methanol conversion in human-made materials, methane-to-methanol catalysis at a monocopper site under ambient conditions is unprecedented," said Matthew O. Ross, a graduate student co-advised by Rosenzweig and Hoffman and the paper's first author.
"If we can develop a complete understanding of how they perform this conversion at such mild conditions, we can optimize our own catalysts."
The study is published in the journal Science.