Analysis with infrared light reveals why enzymes get bogged down trying to break up cellulose.
Using microbes to convert plant residues into sustainably produced fuels, chemicals, and medicines is a key strategy for achieving carbon neutrality. But cellulose, the tough tissue that makes up a large proportion of herbaceous and woody plant bodies, is difficult to break down into its component sugars, which the microbes need to build other useful molecules. A few organisms have evolved specialized enzymes that are able to extract sugars from cellulose-rich plant matter and scientists are keen to understand in greater detail how these enzymes work.
A pair of researchers in the Berkeley Synchrotron Infrared Structural Biology (BSISB) Imaging Program developed a technique that combines a novel microfluidic device and infrared spectroscopy to study how one such cellulose-degrading enzyme works in real time. The experimental system, designed by Hoi-Ying Holman, a senior scientist in Molecular Biophysics and Integrated Bioimaging (MBIB), and postdoctoral researcher Wujun Zhao, and can provide information about how the atomic structure the cellulose changes while the enzyme is working.
Cellulose is composed of long chains of glucose molecules twisted together like rope into structures called fibrils. Hydrogen bonds between the glucose molecules keep them in this tightly organized formation. Scientists have hypothesized that it’s these bonds that obstruct cellulose-chopping enzymes.
By putting the microfluidic device containing cellulose from green algae and tiny amount of an enzyme derived from a fungi in the path of a powerful beam of infrared light generated by the Advanced Light Source (ALS), the researchers confirmed that the hydrogen bonds in the fibrils are indeed acting as roadblocks for the enzymes.
The work, performed in collaboration with researchers from Lawrence Livermore National Laboratory and UC Davis, was recently published in the journal Green Chemistry.
Read more in the Berkeley Lab News Center and the ALS Science Highlight.
