ANN ARBOR—A drug effective at treating animal models of human autoimmune disorders and other diseases works by dialing down the activity of a key enzyme involved in energy production, University of Michigan researchers have found.

“Many drugs block the function of enzymes, essentially turning them off ,” said Gary Glick, who is the Werner E. Bachmann Collegiate Professor of Chemistry at U-M. “Our compound works more like a volume control, so we