Cloned (Comment) | Organism |
---|---|
gene TYR, DNA and amino acid sequence determinatin and analysis, sequence comparisons, recombinant expression of His-tagged intra-melanosomal domain wild-type and mutant variants OCA1A and OCA1B in Trichoplusia ni insect cells using the baculovirus transfection method | Homo sapiens |
recombinant expression of His-tagged intra-melanosomal domain of wild-type tyrosinase and temperature-sensitive OCA1-related mutant R422Q and in whole-insect Trichoplusia ni via transfection with baculovius | Homo sapiens |
Protein Variants | Comment | Organism |
---|---|---|
additional information | generation of the recombinant human tyrosinase intra-melanosomal domain and mutant variants, which mimic genetic changes in both subtypes of OCA1 patients, by site-directed mutagenesis and recombinant expression in insect cells. The recombinant OCA1A show very low protein expression, protein yield, and are enzymatically inactive, while mutants mimicking OCA1B are biochemically similar to the wild-type, but exhibit lower specific activities and protein stabilities than the wild-type enzyme | Homo sapiens |
additional information | the strategy of deleting the membrane-anchoring helix is standard to simplify handling of protein. Deletion of the anchoring helix of the human tyrosinase does not affect the tyrosinase activity | Homo sapiens |
P406L | a phenotype OCA1A-related mutant, inactive mutant | Homo sapiens |
R402Q | a phenotype OCA1A-related mutant, inactive mutant | Homo sapiens |
R422Q | a phenotype OCA1A-related mutant, inactive mutant | Homo sapiens |
R422W | a phenotype OCA1A-related mutant, inactive mutant | Homo sapiens |
R77Q | a phenotype OCA1A-related mutant, inactive mutant | Homo sapiens |
T373K | a phenotype OCA1A-related mutant, inactive mutant | Homo sapiens |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
additional information | - |
additional information | Michaelis-Menten kinetics | Homo sapiens |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
melanosome | - |
Homo sapiens | 42470 | - |
membrane | membrane associated enzyme, deletion of the anchoring helix does not affect the tyrosinase activity | Homo sapiens | 16020 | - |
membrane | tyrosinase is a membrane glycoprotein | Homo sapiens | 16020 | - |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Cu2+ | a copper-containing enzyme, the two copper ions (CuA and CuB) essential for activity | Homo sapiens |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
2 L-dopa + O2 | Homo sapiens | - |
2 dopaquinone + 2 H2O | - |
? | |
tyrosine + O2 | Homo sapiens | - |
dopaquinone + H2O | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Homo sapiens | P14679 | - |
- |
Posttranslational Modification | Comment | Organism |
---|---|---|
glycoprotein | tyrosinase is a membrane glycoprotein | Homo sapiens |
glycoprotein | tyrosinase is a membrane-associated glycoprotein. The purified recombinant human tyrosinase is a soluble monomeric glycoprotein. N-Glycosylation of tyrosinase appears critical for enzyme stability and enzymatic function | Homo sapiens |
Purification (Comment) | Organism |
---|---|
recombinant His-tagged intra-melanosomal domain of wild-type tyrosinase and temperature-sensitive OCA1-related mutant R422Q from whole-insect Trichoplusia ni by nickel affinity chromatography, tag cleavage by TEV protease, dialysis, and two steps of gel filtration, 98.73% purity. The purified recombinant human tyrosinase is a soluble monomeric glycoprotein with an activity that mirrors the tyrosinase in vivo function | Homo sapiens |
recombinant His-tagged intra-melanosomal domain wild-type and mutant variants OCA1A and OCA1B in Trichoplusia ni insect cells by nickel affinity chromatography, ultrafiltration, and gel filtration | Homo sapiens |
Renatured (Comment) | Organism |
---|---|
all proteins including hTyrCtr and OCA1B-related mutant variants are a subjected to equilibrium unfolding/refolding using 0.001 mM protein in 10 mM phosphate buffer, pH 7.4, 5 h at 8 M urea, followed by dilution with 10 mM phosphate buffer, pH 7.4 to 0-8 M urea and incubated for 24 h at room temperature | Homo sapiens |
Source Tissue | Comment | Organism | Textmining |
---|
Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
---|---|---|---|
350.02 | - |
purified recombinant wild-type intra-melanosomal domain, pH 7.4, 37°C | Homo sapiens |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
2 L-dopa + O2 | - |
Homo sapiens | 2 dopaquinone + 2 H2O | - |
? | |
tyrosine + O2 | - |
Homo sapiens | dopaquinone + H2O | - |
? |
Subunits | Comment | Organism |
---|---|---|
? | x * 56630, recombinant enzyme, SDS-PAGE | Homo sapiens |
monomer | x * 57000, recombinant enzyme, SDS-PAGE | Homo sapiens |
Synonyms | Comment | Organism |
---|---|---|
catecholase | - |
Homo sapiens |
cresolase | - |
Homo sapiens |
Diphenol oxidase | - |
Homo sapiens |
L-DOPA monophenolase | - |
Homo sapiens |
OCA1 | - |
Homo sapiens |
tyr | - |
Homo sapiens |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
37 | - |
assay at | Homo sapiens |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7.4 | - |
assay at | Homo sapiens |
General Information | Comment | Organism |
---|---|---|
malfunction | mutations in the tyrosinase gene cause oculocutaneous albinism type 1 (OCA1), an autosomal recessive disease associated with reduced melanin pigment in the hair, skin, and eyes and decreased quality of vision | Homo sapiens |
malfunction | oculocutaneous albinism Type 1 (OCA1) is an autosomal recessive disorder caused by mutations in the tyrosinase gene. Two subtypes of OCA1 exxist, severe OCA1A with complete absence of tyrosinase activity and less severe OCA1B with residual tyrosinase activity. The recombinant OCA1A mutants expressed in insect cells show very low protein expression, protein yield, and are enzymatically inactive, while mutants mimicking OCA1B are biochemically similar to the wild-type, but exhibit lower specific activities and protein stabilities than the wild-type enzyme. OCA1A mutations inactivate tyrosinase and result in severe phenotype, while OCA1B mutations partially inactive tyrosinase and results in OCA1B albinism | Homo sapiens |
metabolism | tyrosinase catalyzes the first two steps of the melanin synthesis pathway: hydroxylation of L-tyrosine to L-3,4-dihydroxyphenylalanine, L-DOPA, monophenolase or cresolase activity, EC1.14.18.1, and the subsequent oxidation of L-DOPA to dopaquinone, diphenol oxidase or catecholase activity, EC 1.10.3.1 | Homo sapiens |
additional information | homology model of human tyrosinase incorporated into the phospholipid membrane, overview | Homo sapiens |
additional information | structure homology modeling of wild-type an dmutant enzymes | Homo sapiens |
physiological function | the enzyme catalyzes the oxidation of L-tyrosine (monophenol substrate) and L-3,4-dihydroxyphenylalanine (L-DOPA, diphenol substrate) to form dopaquinone. The monophenolase and diphenol oxidase activities are linked to the tyrosinase active site, which is composed of six histidine residues that coordinate two copper ions (CuA and CuB) essential for activity | Homo sapiens |