Structural Analysis of Target Protein by Substituted Cysteine Accessibility Method

Substituted Cysteine Accessibility Method (SCAM) is a biochemical approach to investigate the water accessibility or the spatial distance of particular cysteine residues substituted in the target protein. Protein topology and structure can be annotated by labeling with methanethiosulfonate reagents that specifically react with the cysteine residues facing the hydrophilic environment, even within the transmembrane domain. Cysteine crosslinking experiments provide us with information about the distance between two cysteine residues. The combination of these methods enables us to obtain information about the structural changes of the target protein. Here, we describe the detailed protocol for structural analysis using SCAM.