Abstract
BACKGROUND: Proton pump inhibitors (PPIs) are widely prescribed drugs for the treatment of gastroesophageal reflux disease (GERD). Several meta-analysis studies have reported associations between prolonged use of PPIs and major adverse cardiovascular events. However, interaction of PPIs with biological molecules involved in cardiovascular health is incompletely characterized. Dimethylarginine dimethylaminohydrolase (DDAH) is a cardiovascular enzyme expressed in cardiomyocytes, and other somatic cell types in one of two isotypes (DDAH1 and DDAH2) to metabolize asymmetric dimethylarginine (ADMA); a cardiovascular risk factor and competitive inhibitor of nitric oxide synthases (NOSs). METHODS: We performed high throughput drug screening of over 130,000 small molecules to discover human DDAH1 inhibitors and found that PPIs directly inhibit DDAH1. We expressed and purified the enzyme for structural and mass spectrometry proteomics studies to understand how a prototype PPI, esomeprazole, interacts with DDAH1. We also performed molecular docking studies to model the interaction of DDAH1 with esomeprazole. X-ray crystallography was used to determine the structure of DDAH1 alone and bound to esomeprazole at resolutions ranging from 1.6 to 2.9 Å. RESULTS: Analysis of the enzyme active site shows that esomeprazole interacts with the active site cysteine (Cys273) of DDAH1. The structural studies were corroborated by mass spectrometry which indicated that cysteine was targeted by esomeprazole to inactivate DDAH1. CONCLUSIONS: The inhibition of this important cardiovascular enzyme by a PPI may help explain the reported association of PPI use and increased cardiovascular risk in patients and the general population. GENERAL SIGNIFICANCE: Our study calls for pharmacovigilance studies to monitor adverse cardiovascular events in chronic PPI users.