Purdue researchers obtain a snapshot clarifying how materials e...(rystallography to obtain a picture of a ...)

In addition to Davidson, Chen's research team includes postdoctoral research associates Michael Oldham and Dheeraj Khare from Purdue, and professor Florante Quiocho from Baylor College of Medicine. The team began this work in 2001.

ABC proteins are present in every living thing and have important biological functions. Scientists have identified 49 different ABC proteins in humans and have found that more than a dozen disease states are associated with malfunctions of these proteins, including macular dystrophy and problems in the regulation of cholesterol and insulin secretion.

Chen's team isolated ABC proteins from an E. coli bacterium, which is the standard research subject for this field of work. The ABC proteins are structurally very similar to those in human cells, and most of the principles can be directly applied to humans, Chen said.

Membrane proteins are notoriously difficult to study, Chen said. While most proteins dissolve in water and can be easily crystallized and examined, membrane proteins dissolve only in fatty substances, making it hard to isolate them for study.

The collaboration between Chen and Davidson, a structural biologist and a biochemist, was the key to success in capturing the intermediate structure, Chen said.

Davidson identified a special mutant of the ABC protein that locks halfway through the process. The mutant trapped the protein complex in a stable form that allowed Chen to crystallize and visualize the structure.

"We have the common goal to learn how this family of proteins works, but we take different approaches," Chen said. "It is important to communicate with scientists in other fields who can offer clues and tools to help reach your goal. We used genetic data and bio
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