(Santa Barbara, Calif.) An international team of researchers has reported a new understanding of a little-known process that happens in virtually every cell of our bodies.
Protein folding is the process by which not-yet folded chains of amino acids assume their specific shapes, hence taking on their specific functions. These functions vary widely: In the human body, proteins fold to become muscles, hormones, enzymes, and various other components.
"This protein folding process is still a big mystery," said UC Santa Barbara physicist Everett Lipman, one of several authors of a paper, "Quantifying internal friction in unfolded and intrinsically disordered proteins with single-molecule spectroscopy." The paper was published in the Proceedings of the National Academy of Sciences.
A protein's final shape, said Lipman, is primarily determined by the sequence of amino acid components in the unfolded chain. In the process, the components bump up against each other, and when the right configuration is achieved, the chain passes through its "transition state" and snaps into place.
"What we would like to understand eventually is how the chemical sequence of a protein determines what it is going to become and how fast it is going to get there," Lipman said.
Using a microfluidic mixing technique pioneered in the UCSB physics department by former graduate student Shawn Pfeil, the research team, including collaborators from the University of Zurich and the University of Texas, was able to monitor extremely rapid reconfiguration of individual protein molecules as they folded.
In the microfluidic mixer, a "denaturant" chemical used to unravel the proteins was quickly diluted, enabling observation of folding under previously inaccessible natural conditions. The measurements demonstrated that internal friction plays a more significant role in the folding process than could be seen in prior experiments, especially when t
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University of California - Santa Barbara