Molybdenum cofactor sulfurase (MOCOS)

Molybdenum cofactor sulfurase (MOCOS) is an enzyme that catalyzes the transfer of a terminal sulfur atom to the molybdenum cofactor (Moco), a key post-translational modification needed for the activation of the xanthine dehydrogenase (XDH) and aldehyde oxidase (AO) family of enzymes in humans[3][2][1]. This sulfur transfer is essential for the final maturation step of these enzymes; without it, active catalysis of hypoxanthine to uric acid and aldehyde substrates cannot occur. Mutations in the MOCOS gene cause type II xanthinuria, characterized by low uric acid, accumulation of xanthine/hypoxanthine, and risk of urinary xanthine stones or tissue xanthine deposits[3]. MOCOS is structurally related to other sulfurtransferases and functions through distinct N-terminal (cysteine desulfurase-like) and C-terminal (MOSC domain) regions, collaborating in the relay of persulfide sulfur to the cofactor[1][2]. While not a direct drug target, MOCOS's function is central to the activity and pharmacokinetics of drugs metabolized by XDH and AO, such as allopurinol and certain prodrugs[3]. Disruption of MOCOS thus affects purine metabolism, drug breakdown, and can underlie rare metabolic disorders.

Other names

MCSMOSMoCo sulfurasehMCSHMCSFLJ20733Molybdenum cofactor sulfurtransferasehuman molybdenum cofactor sulfurasemolybdenum cofactor sulfurase (human)MOCOS

Sulfur transfer to the molybdenum cofactor, enabling activation of downstream molybdenum-dependent enzymes such as xanthine dehydrogenase and aldehyde oxidase[3][2][1] Reductive activation of prodrugs (e.g., amidoximes) in in vitro systems[3]