Protein Variants | Comment | Organism |
---|---|---|
additional information | molybdopterin enzyme periplasmic nitrate reductase (NapA, EC 1.9.6.1) is utilized as a vehicle to understand the substrate preference and delineate the kinetic underpinning of the differences imposed by exchanging the molybdenum ligands. The Mo-coordinating residue mutant C176D of NapA (EC 1.9.6.1), constructed by site-directed mutagenesis, is active with DMSO (and artificial cosubstrate methyl viologen), while the wild-type NapA is not. Kinetic consequences of the exchange of the endogenous ligand to molybdenum with other ligands within the cofactor of DMSO reductase family enzymes, overview. The C176D NapA variant shows attenuated nitrate reductase activity with a kcat 17times lower than the native NapA enzyme and a Km for nitrate that is 1.5times higher than the Km for nitrate reduction by the C176S NapA variant. Proposed interaction of the Asp ligand with bound DMSO compared to a Cys ligand at the active site in NapA variants | Escherichia coli |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.0282 | - |
Dimethylsulfoxide | pH 6.0, 25°C, recombinant NapA mutant C176D | Escherichia coli |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Molybdenum | required | Escherichia coli |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Escherichia coli | - |
- |
- |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
dimethylsulfoxide + methyl viologen | activity of mutant C176D of periplasmic nitrate reductase NapA (EC 1.9.6.1), no activity with wild-type NapA or C176S/A NapA mutants | Escherichia coli | dimethylsulfide + oxidized methyl viologen + H2O | - |
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Synonyms | Comment | Organism |
---|---|---|
dimethyl sulfoxide reductase | - |
Escherichia coli |
DMSO reductase | - |
Escherichia coli |
DMSOR | - |
Escherichia coli |
More | see also Ec 1.9.6.1 | Escherichia coli |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | - |
assay at | Escherichia coli |
Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.023 | - |
Dimethylsulfoxide | pH 6.0, 25°C, recombinant NapA mutant C176D | Escherichia coli |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
6 | - |
recombinant NapA mutant C176D | Escherichia coli |
pH Minimum | pH Maximum | Comment | Organism |
---|---|---|---|
5 | 9 | activity range, recombinant NapA mutant C176D | Escherichia coli |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
methyl viologen | - |
Escherichia coli | |
molybdenum cofactor | MoCo, the cofactor coordinates organic molybdopterin to molybdenum, over 50 different molybdopterin enzymes are known to catalyze a variety of chemistries in the cycling of C, N, S, As, and Se, all relying on the same basic cofactor, the MoCo. Kinetic consequences of the exchange of the endogenous ligand to molybdenum with other ligands within the cofactor of DMSO reductase family enzymes, overview. The mutant C176D of periplasmic nitrate reductase NapA (EC 1.9.6.1) is active with DMSO (and artificial cosubstrate methyl viologen), while the wild-type NapA is not | Escherichia coli |
General Information | Comment | Organism |
---|---|---|
evolution | respiratory enzyme members of the DMSOR family such as nitrate reductase (NR, EC 1.9.6.1), dimethyl sulfoxide reductase (DMSOR, EC 1.8.5.3), trimethylamine N-oxide reductase (TMAOR, EC 1.7.2.3), and formate dehydrogenase (FDH) contribute to this broad diversity. The DMSOR family of enzymes has diverse active sites that vary in the first coordination sphere of the molybdenum center. Many enzymes in the DMSOR family use oxygen atom transfer (OAT) reactions for substrate transformation, e.g. periplasmic nitrate reductase (Nap) and respiratory nitrate reductase (Nar) reduce nitrate to nitrite, TMAOR reduces TMAO to TMA, and DMSOR reduces DMSO to dimethyl sulfide (DMS). Enzymes that catalyze the same reaction, such as Nap and Nar, have different molybdenum coordination spheres. In NapA, molybdenum is coordinated by a cysteine residue in the 5th position and an oxo or a sulfido group in the 6th | Escherichia coli |
kcat/KM Value [1/mMs-1] | kcat/KM Value Maximum [1/mMs-1] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.816 | - |
Dimethylsulfoxide | pH 6.0, 25°C, recombinant NapA mutant C176D | Escherichia coli |