A proteomic study of S-nitrosylation in the rat cardiac proteins in vitro

Protein S-nitrosylation in the heart tissue has been implicated in several patho (physiological) processes. However, specific protein targets for S-nitrosylation remain largely unknown. In this study, the rat cardiac proteins were incubated in vitro with S-nitrosoglutathione (GSNO), a biologically existing nitric oxide (NO) donor and S-nitrosating agent, to induce protein S-nitrosylation, and the resulting S-nitrosylated proteins were purified by the biotin switch method, followed by two-dimensional gel electrophoresis (2-DE) separation and matrix-assisted laser desorption ionization/time of flight tandem mass spectrometry (MALDI-TOF-MS/MS) identification. Candidate Western blot analysis was also used to identify potential S-nitrosylated proteins. A total of ten proteins including triosephosphate isomerase, glyceraldehyde-3-phosphate dehydrogenase, creatine kinase, adenylate kinase 1 (AK1), enolase 1, destrin, actin, myosin, albumin and Hsp27 were unambiguously identified, among which AK1 was found as a novel target of S-nitrosylation. Further studies showed that AK1 activity in the rat heart extracts was significantly inhibited by GSNO but not oxidized glutathione (GSSG), and the inhibition was completely reversed by dithiothreitol (DTT) post-treatment, demonstrating that S-nitrosylation might serve as a new regulatory mechanism in controlling AK1 activity. This study represents an initial attempt to characterize the S-nitrosoproteome in the heart and highlights the importance of protein S-nitrosylation in cardio function regulation.