Extended Data Fig. 7. Chemical functions of lysine and cysteine residues forming NOS and SONOS bridges in proteins.

Chemical functions of lysine and cysteine residues forming NOS and SONOS bridges in proteins. Four major functional categories could be identified including i) lysines with catalytic roles in enzyme mechanisms, ii) lysines involved in binding of enzyme substrates, nucleic acids and effectors, iii) cysteines with catalytic roles in enzyme mechanisms and iv) allosteric bridges, which are located remotely relative to the active/functional site. Structures of key reaction intermediates and interaction partners are highlighted. Note that these functions are exerted under reducing conditions that is in the absence of NOS/SONOS bridges. Formation of the NOS or SONOS bridge under oxidizing conditions leads to either a loss-of-function (catalytic lysines, catalytic cysteines), diminished biologial activity (lysine with binding roles) or modulated function (allosteric switches). Specific information about all proteins regarding origin, biological function, type of NOS/SONOS redox switch, suggested mechanism of the redox switch and potential relevance in disease states is compiled in Supplementary Tables 2 and 3.