Iron sulfur clusters are common cofactors found in almost all living organisms. They have diverse biological functions, ranging from electron transfer and catalysis to regulation of gene expression and enzyme activity.

Sulfurous acid is hypothesized to be a nucleation center for aerosols, but its isolation and characterization have been described as one of the greatest challenges of inorganic chemistry. Consequently, most information about sulfurous acid has come from the more than twenty theoretical studies examining it.

Post Translational Modifications (PTM) are modifications which take place following protein biosynthesis. There are hundreds of PTMs which have been discovered and possibly many more which have yet to be discovered. The analysis of the 20 amino acids to study has exponentially increased to seemingly limitless combinations of proteins and PTMs, and this number of possible PTM combinations add daunting challenges for proteomic analysis.

Scanning probe microscopy methodologies have advanced to the point that in situ measurements of complex biological systems can be routinely measured at the single-molecule level¹, providing information on rare states that can be lost in standard ensemble measurements²and allowing highly specific detection of various proteins and polysaccharides^3,4.