A structure‐based approach for detection of thiol oxidoreductases and their catalytic redox‐active cysteine residues

Abstract

Cysteine (Cys) residues often play critical roles in proteins, for example, in the formation of structural disulfide bonds, metal binding, and various catalytic functions. Thiol oxidoreductases, enzymes containing catalytic redox‐active Cys residues (redox Kat Cys), have been extensively studied, but even for these proteins there is little understanding of what distinguishes their redox Cys from other Cys functions. Herein, we characterized thiol oxidoreductases at a structural level and developed an algorithm that can efficiently recognize them by (i) analyzing amino acid and secondary structure composition of the active site and its similarity to known active sites containing redox Kat Cys, and (ii) calculating accessibility, active site location and reactivity of Cys. By applying this procedure to the Saccharomyces cerevisiae proteome, we could identify the majority of known yeast thiol oxidoreductases. This study provides insights into the structural properties of redox Kat Cys and highlights important differences between these residues and other reactive Cys. It should help recognize novel thiol oxidoreductases in structure databases.