Cloned (Comment) | Organism |
---|---|
DNA and amino acid sequence determination and analysis, human enzyme expression in Escherichia coli | Homo sapiens |
Protein Variants | Comment | Organism |
---|---|---|
E254D | site-directed mutagenesis, the mutant shows 5% remaining activity compared to the wild-type enzyme | Homo sapiens |
additional information | human 4-HPPD possesses an extended C-terminus compared to other 4-HPPD enzymes. Successive truncation of the disordered tail which follows the final alpha-helix results in no changes in the Km value for 4-HPP substrate but the kcat values are significantly reduced by ca. 25 to 50%. The different conformation of E254, R378 and Q375 in the final helix might be the cause of the activity loss | Homo sapiens |
Q375N | site-directed mutagenesis, the mutant shows that a solvent accessible channel opens to the putative substrate binding site, suggesting this is responsible for the complete loss of activity, modeling, overview. Inactive mutant | Homo sapiens |
Q375N/R378K | site-directed mutagenesis, inactive mutant | Homo sapiens |
R378K | site-directed mutagenesis, the mutant shows 5% remaining activity compared to the wild-type enzyme | Homo sapiens |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.07 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAL381 | Homo sapiens | |
0.08 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, wild-type enzyme and mutant DELTAG388 | Homo sapiens | |
0.09 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAL385 | Homo sapiens | |
0.11 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant E254D | Homo sapiens | |
0.12 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAG379 | Homo sapiens | |
0.24 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant R378K | Homo sapiens | |
0.3 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAN380 | Homo sapiens |
Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
---|---|---|---|
45000 | - |
2 * 45000, SDS-PAGE | Homo sapiens |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
4-hydroxyphenylpyruvate + O2 | Homo sapiens | the conversion of 4-hydroxyphenyl-pyruvate to homogentisate involves oxidative decarboxylation, side-chain migration and aromatic hydroxylation in a single catalytic cycle. The 4-HPPD reaction is unusual in that the 2-oxoacid and prime substrate moieties are contained within the same molecule | homogentisate + CO2 | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Homo sapiens | P32754 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant enzyme 15fold from Escherichia coli by anion-exchange and hydrophobic interaction chromatography, and gel filtration | Homo sapiens |
Source Tissue | Comment | Organism | Textmining |
---|---|---|---|
Hep-G2 cell | - |
Homo sapiens | - |
Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
---|---|---|---|
0.04 | - |
purified recombinant mutant R378K, pH 6.5, 37°C, homogentisate production | Homo sapiens |
0.06 | - |
purified recombinant mutant E254D, pH 6.5, 37°C, O2 consumption | Homo sapiens |
0.07 | - |
purified recombinant mutant R378K, pH 6.5, 37°C, O2 consumption | Homo sapiens |
0.2 | - |
purified recombinant mutant E254D, pH 6.5, 37°C, homogentisate production | Homo sapiens |
2.6 | - |
purified recombinant wild-type enzyme, pH 6.5, 37°C, O2 consumption | Homo sapiens |
2.8 | - |
purified recombinant wild-type enzyme, pH 6.5, 37°C, homogentisate production | Homo sapiens |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
4-hydroxyphenylpyruvate + O2 | - |
Homo sapiens | homogentisate + CO2 | - |
? | |
4-hydroxyphenylpyruvate + O2 | the conversion of 4-hydroxyphenyl-pyruvate to homogentisate involves oxidative decarboxylation, side-chain migration and aromatic hydroxylation in a single catalytic cycle. The 4-HPPD reaction is unusual in that the 2-oxoacid and prime substrate moieties are contained within the same molecule | Homo sapiens | homogentisate + CO2 | - |
? |
Subunits | Comment | Organism |
---|---|---|
homodimer | 2 * 45000, SDS-PAGE | Homo sapiens |
More | five residues of the N-terminus in recombinant 4-HPPD are TTYSD | Homo sapiens |
Synonyms | Comment | Organism |
---|---|---|
4-HPPD | - |
Homo sapiens |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
37 | - |
assay at | Homo sapiens |
Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.06 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant E254D | Homo sapiens | |
0.07 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant R378K | Homo sapiens | |
0.1 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAG379 | Homo sapiens | |
0.5 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAN380 | Homo sapiens | |
1 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAL381 | Homo sapiens | |
1.4 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAG388 and DELTAL385 | Homo sapiens | |
2.2 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, wild-type enzyme | Homo sapiens |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
6.5 | - |
assay at | Homo sapiens |
General Information | Comment | Organism |
---|---|---|
evolution | the enzyme belongs to the non-haem Fe(II)/2-oxoacid-dependent oxygenase superfamily, which couples the oxidative decarboxylation of a 2-oxoacid (most commonly a-ketoglutarate) to the oxidation of the prime substrate | Homo sapiens |
malfunction | deficiency in active 4-HPPD in humans results in type III tyrosinemia, a rare autosomal recessive disorder | Homo sapiens |
metabolism | enzyme 4-HPPD catalyzes the second step in the pathway of tyrosine catabolism, the conversion of 4-hydroxyphenyl-pyruvate to homogentisate | Homo sapiens |
additional information | the disordered C-terminal tail of the enzyme, which is extended C-terminus compared to other 4-HPPD enzymes, plays an important role in catalysis with a critical role of residue Q375 in orientating the tail and ensuring the conformation of the terminal alpha-helix to maintain the integrity of the active site for catalysis. The active site of 4-HPPD is enclosed by a C-terminal alpha-helix which is assumed to function as a gate which controls access of substrate. Interactions provided by Q375 to hold the terminal helix and the tail in proper position are critical for isolating the active site from solvent during catalysis, enzyme structure modeling, overview | Homo sapiens |
kcat/KM Value [1/mMs-1] | kcat/KM Value Maximum [1/mMs-1] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.27 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant R378K | Homo sapiens | |
0.57 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant E254D | Homo sapiens | |
0.9 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAG379 | Homo sapiens | |
1.5 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAN380 | Homo sapiens | |
14 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAL381 | Homo sapiens | |
16 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAL385 | Homo sapiens | |
17 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, mutant DELTAG388 | Homo sapiens | |
29 | - |
4-hydroxyphenylpyruvate | pH 6.5, 37°C, wild-type enzyme | Homo sapiens |