Protein S-nitrosylation (or S-nitrosylation) is the covalent redox-related modification of a cysteine sulfhydryl group with nitric oxide (NO). It is becoming increasingly recognized as a ubiquitous regulatory reaction comparable to phosphorylation. A growing number of proteins has been found to undergo S-nitrosylation in vivo, including hemoglobin, NF-.B p50, protein-tyrosine phosphatases and several caspases. Such S-nitrosylation results in altered function. For example, S-nitrosylation of NF-.B p50 modifies its function in mediating changes in expression of target genes. The inhibition of protein-tyrosine phosphatases by S-nitrosylation is critical in regulating cellular signal transduction pathways. Hence, S-nitrosylation may function as an important regulatory mechanism for fine-tuning protein activities within diverse cellular processes and biochemical pathways, including signal transduction, DNA repair, ion channel regulation and apoptosis. In addition, recent studies have suggested that S-nitrosylation may play key roles in a broad range of human diseases. For example, an abnormal increase of protein S-nitrosylation events has been reported in patients with diabetes, multiple sclerosis, tuberculosis and asthma.

CysNO-DB provides retrievals of S-nitrosylation status and possible site information for proteins from all species. Most of these proteins were identified from human and mouse at the moment. The database consists of S-nitrosylation sites found in the recent study of Dr. Shi-Jian Ding.s lab and other published literatures as well as links of extensive protein information such as protein ontologies, post-translational modifications and signaling pathways. In addition, a well developed prediction tool will be integrated to discover potential S-nitrosylation sites in peptides and proteins of particular interest.