Although understanding the molecular movement of proteins in regards to how the arrangement and structure of their atoms changes as they interact is an important part of human biology, this process has been difficult to capture. Now, a team of scientists from the University of Wisconsin - Milwaukee (UWM) has captured these processes in real time using the fastest-ever molecular imaging technique to obtain images of a tiny crystallized protein as it reacts to light.
The new experiment documents the molecular movement of proteins in increments of just a few quadrillionths of a second and could help scientists better understand how these complex molecules sustain the processes integral to life.
"This puts us dramatically closer to understanding the chemistry necessary for all life," said Marius Schmidt, a UWM physics professor and senior author of the study. "Discovering the step-by-step process of how proteins function is necessary not only to inform treatment of disease, but also to shed light on the grand questions of biology."
Understanding the atomic changes in protein molecules in real time is important because their structure determines their function, and the new study sheds light on these unique dynamics.
"Light drives much of biology and this novel experiment is a pinnacle in understanding how living systems respond to light," said Keith Moffat, a University of Chicago professor and co-author of the study.
The team used the Linac Coherent Light Source molecular imaging technique in order to map the atoms of a protein in real time as the chemical bonds of a dye molecule rearranged. The structure of this molecule, which was yellow, was captured in an electronically excited state, an essential state for light perception in all living organisms.
"Once the protein absorbs a photon of light, it changes its shape from an initial configuration, known as the 'trans' form, to a new shape, known as 'cis,'" said Petra Fromme, director of the Biodesign Center for Applied Structural Discovery at Arizona State University and co-author of the study. "The transition occurs in such a unbelievably brief time span that nobody had been able to see the important details of this process - until our discovery."
The team hopes to build upon its findings by obtaining femtosecond detail over a bigger range of time in order to gain a larger amount of information on the molecular movement of the crystallized protein as it responds to light and potentially allow them to control protein function using light.
"We're interested in the mechanism of the chemical reaction, with the goal of controlling and steering it in a certain direction with light," Schmidt said. "We can shape laser pulses for that purpose. We will discover how the molecules march in synchrony during such processes."
The findings were published in the May 6 issue of Science.
