Any feedback?
Please rate this page
(literature.php)
(0/150)

BRENDA support

Literature summary extracted from

  • Davis, A.C.; Johnson-Winters, K.; Arnold, A.R.; Tollin, G.; Enemark, J.H.
    Kinetic results for mutations of conserved residues H304 and R309 of human sulfite oxidase point to mechanistic complexities (2014), Metallomics, 6, 1664-1670 .
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

EC Number Cloned (Comment) Organism
1.8.3.1 recombinant expression of wild-type and mutant enzymes Homo sapiens

Protein Variants

EC Number Protein Variants Comment Organism
1.8.3.1 H304A R309H site-directed mutagenesis, a mutation that removes the charge, hydrogen bonding, and is of smaller size, shows a decrease in Ksulfite m , thus binding sulfite more efficiently than the wild-type, kcat is increased compared to wild-type Homo sapiens
1.8.3.1 H304R/R309H site-directed mutagenesis, the mutant shows altered kinetics and reaction rates compared to the wild-type enzyme Homo sapiens
1.8.3.1 K322R site-directed mutagenesis, the mutant shows altered kinetics and reaction rates compared to the wild-type enzyme Homo sapiens
1.8.3.1 additional information all of the mutants show decreased rates of intramolecular electron transfer (IET) but increased steady-state rates of catalysis, IET is not the rate determining step for any of the mutations. Redox potentials of wild-tyype and mutant enzymes, overview Homo sapiens
1.8.3.1 R160Q site-directed mutagenesis, inactive mutant Homo sapiens
1.8.3.1 R309E site-directed mutagenesis, the mutant shows altered kinetics and reaction rates compared to the wild-type enzyme, mutant R309E, which shows the greatest increase in activity, also shows the greatest increase in Km Homo sapiens
1.8.3.1 R309H site-directed mutagenesis, the mutant shows altered kinetics and reaction rates compared to the wild-type enzyme, purified R309H mutant enzyme has substantially increased catalytic activity and a slightly less efficient Km sulfite compared to the wild-type enzyme Homo sapiens

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
1.8.3.1 additional information
-
 additional information Michaelis-Menten steady-state kinetics of wild-type and mutant enzymes. All of the mutants show decreased rates of intramolecular electron transfer (IET) but increased steady-state rates of catalysis Homo sapiens

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
1.8.3.1 Fe3+
-
 Homo sapiens
1.8.3.1 Mo6+
-
 Homo sapiens

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
1.8.3.1 sulfite + O2 + H2O Homo sapiens
-
 sulfate + H2O2
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
1.8.3.1 Homo sapiens P51687
-
-

Purification (Commentary)

EC Number Purification (Comment) Organism
1.8.3.1 recombinant wild-type and mutant enzymes Homo sapiens

Reaction

EC Number Reaction Comment Organism Reaction ID
1.8.3.1 sulfite + O2 + H2O = sulfate + H2O2 catalytic cycle and electron transfer steps, and proposed oxidation state changes occurring at the Mo and Fe centers of one subunit of human sulfite oxidase during the catalytic oxidation of sulfite and the concomitant reduction of (cyt c)ox, overview Homo sapiens
a

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1.8.3.1 additional information regeneration of the enzyme includes two, one-electron intramolecular electron transfers (IET) from the molybdenum (Mo) to the heme Fe and two, one-electron intermolecular electron transfers from the Fe to external ferricytochrome c Homo sapiens ?
-
 ?
1.8.3.1 sulfite + O2 + H2O
-
 Homo sapiens sulfate + H2O2
-
 ?

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
1.8.3.1 25
-
 assay at Homo sapiens

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
1.8.3.1 6.8 7.6 assay at Homo sapiens

Cofactor

EC Number Cofactor Comment Organism Structure
1.8.3.1 cytochrome c
-
 Homo sapiens
1.8.3.1 heme
-
 Homo sapiens
1.8.3.1 molybdenum cofactor three conserved residues (H304, R309, K322) are hydrogen bonded to the phosphate group of the molybdenum cofactor Homo sapiens

General Information

EC Number General Information Comment Organism
1.8.3.1 malfunction R309H and K322R mutations are responsible for isolated sulfite oxidase deficiency Homo sapiens