Their study, published Dec. 5 in the journal Cell, focuses on nitric oxide, a compound that dilates blood vessels, improves memory, fights infection and stimulates the release of hormones, among other functions. How nitric oxide performs these activities had long been a mystery.

The researchers discovered a novel “carrier” enzyme (called SNO-CoA-assisted nitrosylase, or SCAN) that attaches nitric oxide to proteins, including the receptor for insulin action.

They found that the SCAN enzyme was essential for normal insulin action, but also discovered heightened SCAN activity in diabetic patients and mice with diabetes. Mouse models without the SCAN enzyme appeared to be shielded from diabetes, suggesting that too much nitric oxide on proteins may be a cause of such diseases.

“We show that blocking this enzyme protects from diabetes, but the implications extend to many diseases likely caused by novel enzymes that add nitric oxide,” said the study’s lead researcher Jonathan Stamler, the Robert S. and Sylvia K. Reitman Family Foundation Distinguished Professor of Cardiovascular Innovation at the Case Western Reserve School of Medicine and president of Harrington Discovery Institute at University Hospitals. “Blocking this enzyme may offer a new treatment.”