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Literature summary for 4.2.1.96 extracted from

  • Rebrin, I.; Thoeny, B.; Bailey, S.W.; Ayling, J.E.
    Stereospecificity and catalytic function of histidine residues in 4alpha-hydroxy-tetrahydropterin dehydratase/DCoH (1998), Biochemistry, 37, 11246-11254.
    View publication on PubMed
Search for more literature for 4.2.1.96

Protein Variants

Protein Variants Comment Organism
H61A mutant enzyme H61A shows no dehydratase activity with 4a(R)-hydroxy-6(R)-methyltetrahydropterin. Mutant enzyme H79A shows no dehydratase activity with 4a(S)-hydroxy-6(R)-methyltetrahydropterin. The Km-value for 4a(S)-hydroxy-6(R)-methyltetrahydropterin is comparable to the Km-value of the wild type enzyme. The turnover number of the mutant enzyme H62A is 24% of that with the wild type enzyme for the 4a(R),6(S)-isomer and the 4a(S),6(R)-isomer Rattus norvegicus

Inhibitors

Inhibitors Comment Organism Structure
diethyldicarbonate inactivation is complete when about 1.2 His per subunit are derivatized Rattus norvegicus
Quinoid 6(S)-propyldihydropterin
-
 Rattus norvegicus

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.0015
-
 4a(S)-hydroxy-6(R)-methyltetrahydropterin wild type enzyme Rattus norvegicus
0.0025
-
 4a(S)-hydroxy-6(R)-methyltetrahydropterin mutant enzyme H79A Rattus norvegicus
0.006
-
 4a(R)-hydroxy-6(S)-methyltetrahydropterin wild type enzyme Rattus norvegicus
0.03
-
 4a(S)-hydroxy-6(R)-methyltetrahydropterin mutant enzyme H62A Rattus norvegicus
330
-
 4a(R)-hydroxy-6(S)-methyltetrahydropterin mutant enzyme H62A Rattus norvegicus
390
-
 4a(R)-hydroxy-6(S)-methyltetrahydropterin mutant enzyme H61A Rattus norvegicus

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
11800
-
 4 * 11800, mutant enzyme H61A, H62A and H79A, electrospray mass spectrometry Rattus norvegicus
11867
-
 4 * 11867, wild type enzyme, electrospray mass spectrometry Rattus norvegicus
12000
-
 4 * 12000, SDS-PAGE Rattus norvegicus
46000
-
 HPLC gel filtration Rattus norvegicus

Organism

Organism UniProt Comment Textmining
Rattus norvegicus P61459
-
-

Reaction

Reaction Comment Organism Reaction ID
4a-hydroxytetrahydrobiopterin = 6,7-dihydrobiopterin + H2O His61 and His79 act as acid catalysts for the stereospecific elimination of the 4a(R)- and 4a(S)-hydroxyl groups, respectively. The role of His62 is primarily binding substrate with additional component of base catalysis Rattus norvegicus
a

Source Tissue

Source Tissue Comment Organism Textmining
liver
-
 Rattus norvegicus
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
4a(R)-hydroxy-6(S)-methyltetrahydropterin
-
 Rattus norvegicus quinoid 6(S)-methyldihydropterin
-
 ?
4a(S)-hydroxy-6(R)-methyltetrahydropterin
-
 Rattus norvegicus quinoid 6(R)-methyldihydropterin
-
 ?
4a-Hydroxy-6(S)-methyltetrahydropterin
-
 Rattus norvegicus Quinoid 6(S)-methyldihydropterin
-
 ?

Subunits

Subunits Comment Organism
tetramer 4 * 11800, mutant enzyme H61A, H62A and H79A, electrospray mass spectrometry Rattus norvegicus
tetramer 4 * 11867, wild type enzyme, electrospray mass spectrometry Rattus norvegicus
tetramer 4 * 12000, SDS-PAGE Rattus norvegicus

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
2.4
-
 4a(S)-hydroxy-6(R)-methyltetrahydropterin mutant enzyme H62A Rattus norvegicus
7.5
-
 4a(S)-hydroxy-6(R)-methyltetrahydropterin mutant enzyme H79A Rattus norvegicus
8.6
-
 4a(R)-hydroxy-6(S)-methyltetrahydropterin mutant enzyme H61A Rattus norvegicus
8.9
-
 4a(R)-hydroxy-6(S)-methyltetrahydropterin mutant enzyme H62A Rattus norvegicus
10
-
 4a(R)-hydroxy-6(S)-methyltetrahydropterin wild type enzyme Rattus norvegicus
10
-
 4a(S)-hydroxy-6(R)-methyltetrahydropterin wild type enzyme Rattus norvegicus