{Moco}n, (n = 0–8): A general formalism for describing the highly covalent molybdenum cofactor of sulfite oxidase and related Mo enzymes,

Bringing Nitric Oxide to the Molybdenum World—A Personal Perspective

“…Molybdenum-containing enzymes are responsible for the biological handling of dinitrogen (Nitrogenase, Equation ( 1)), nitrate (Nitrate reductase (NaR), Equation ( 2)), sulfite (Sulfite oxidase (SO), Equation ( 3)), dimethylsulfoxide (dimethylsulfoxide reductase (DMSOR), Equation ( 4)), aldehydes (Aldehyde oxidase (AO), Equation ( 5)), xanthine (Xanthine oxidase (XO), Equation ( 6)) and carbon dioxide (Carbon dioxide dehydrogenase, Equation (7), and Formate dehydrogenase, Equation ( 8 With the single (as far as is presently known) exception of nitrogenase [9][10][11][12], molybdenum is found coordinated by the cis-dithiolene group (-S-C=C-S-) of one or two molecules of a pyranopterin cofactor (Figure 1). In a parallel situation to the haem ring, this unique cofactor is not an "innocent scaffold" and it is considered to be co-responsible to modulate the active site reactivity, besides acting as a "wire" to conduct the electrons to, or from, the other redox-active centres of the enzyme (intramolecular electron transfer, when this is the case) [13][14][15][16][17][18][19][20]. In addition to the pyranopterin cofactor, the molybdenum ion is coordinated by oxygen and/or sulfur and/or selenium terminal atoms and/or by enzyme-derived amino acid residues (Figure 1), which are also expected to have key roles in catalysis (although their individual roles are not yet understood in many molybdoenzymes).…”

“…With the single (as far as is presently known) exception of nitrogenase [9][10][11][12], molybdenum is found coordinated by the cis-dithiolene group (-S-C=C-S-) of one or two molecules of a pyranopterin cofactor (Figure 1). In a parallel situation to the haem ring, this unique cofactor is not an "innocent scaffold" and it is considered to be co-responsible to modulate the active site reactivity, besides acting as a "wire" to conduct the electrons to, or from, the other redox-active centres of the enzyme (intramolecular electron transfer, when this is the case) [13][14][15][16][17][18][19][20]. In addition to the pyranopterin cofactor, the molybdenum ion is coordinated by oxygen and/or sulfur and/or selenium terminal atoms and/or by enzyme-derived amino acid residues (Figure 1), which are also expected to have key roles in catalysis (although their individual roles are not yet understood in many molybdoenzymes).…”

Multichannel Sensor for Detection of Molybdenum Ions Based on Nitrogen-Doped Carbon Quantum Dot Ensembles

“…For instance, Cu is vital for many living organisms and plays an important role in physiological and pathological processes, such as bone formation and cellular respiration [1]. Mo acts as an enzymatic cofactor of several enzymes (such as aldehyde oxidase, sulfite oxidase, and xanthine oxidase dehydrogenase), which catalyzes several substrates' hydroxylation [2]. However, abnormal levels of these elements in the human body pose a severe threat, since it may cause distinct diseases.…”