Crystallization (Comment) | Organism |
---|---|
enzyme complexes phosphate-hAPRT, hypoxanthine-PRPP-Mg2+-hAPRT, IMP-hAPRT, and GMP-hAPRT, mixing of 400 nl of 5 mg/ml protein complexes in 20 mM Tris-HCl, pH 7.4, 5 mM MgCl2, with 200 nl of crystallization solution made of 85 mM Tris-HCl, pH 8.5, 170 mM NaOAc, 19-21% PEG 4000, and 0-30% glycerol, overnight at 20°C, X-ray diffraction structrue determination and analysis at resolution 1.55-1.90 A, molecular replacement using the structure with PDB ID 6FCH as template, and modeling | Homo sapiens |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
additional information | - |
additional information | Michaelis-Menten kinetics | Homo sapiens |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | required, enzyme binding structure, overview | Homo sapiens |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
adenine + 5-phospho-alpha-D-ribose 1-diphosphate | Homo sapiens | - |
AMP + diphosphate | - |
r |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Homo sapiens | P07741 | - |
- |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
AMP + diphosphate = adenine + 5-phospho-alpha-D-ribose 1-diphosphate | molecular reaction mechanism in both directions of the reaction for hAPRT: in the forward reaction, SN2-type molecular mechanism including some SN1 characteristics, and in the reverse reaction, a proposed magnesium-assisted SN2-type mechanism, detailed overview | Homo sapiens |
Source Tissue | Comment | Organism | Textmining |
---|---|---|---|
commercial preparation | - |
Homo sapiens | - |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
adenine + 5-phospho-alpha-D-ribose 1-diphosphate | - |
Homo sapiens | AMP + diphosphate | - |
r | |
adenine + 5-phospho-alpha-D-ribose 1-diphosphate | binding to hAPRT is substrate shape-specific in the forward reaction, whereas it is base-specific in the reverse reaction | Homo sapiens | AMP + diphosphate | - |
r | |
additional information | although hypoxanthine and adenine have the same chemical skeleton, which differs only by a hydroxyl instead of an amine at the C6 position away from the reactive N9 nitrogen, adenine seems to be the only purine metabolized by hAPRT | Homo sapiens | ? | - |
- |
Synonyms | Comment | Organism |
---|---|---|
APRT | - |
Homo sapiens |
hAPRT | - |
Homo sapiens |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
23 | - |
assay at | Homo sapiens |
Temperature Stability Minimum [°C] | Temperature Stability Maximum [°C] | Comment | Organism |
---|---|---|---|
47.6 | - |
unfolding temperature of enzyme hAPRT with hypoxanthine | Homo sapiens |
49.6 | - |
unfolding temperature of enzyme hAPRT | Homo sapiens |
50.3 | - |
unfolding temperature of enzyme hAPRT with adenine | Homo sapiens |
51.2 | - |
unfolding temperature of enzyme hAPRT with IMP | Homo sapiens |
52.1 | - |
unfolding temperature of enzyme hAPRT with diphosphate | Homo sapiens |
53 | - |
unfolding temperature of enzyme hAPRT with GMP | Homo sapiens |
53.5 | - |
unfolding temperature of enzyme hAPRT with diphosphate and IMP | Homo sapiens |
53.6 | - |
unfolding temperature of enzyme hAPRT with diphosphate and GMP | Homo sapiens |
59 | - |
unfolding temperature of enzyme hAPRT with AMP | Homo sapiens |
64.3 | - |
unfolding temperature of enzyme hAPRT with diphosphate and AMP | Homo sapiens |
79.6 | - |
unfolding temperature of enzyme hAPRT with PRPP | Homo sapiens |
79.7 | - |
unfolding temperature of enzyme hAPRT with PRPP and hypoxanthine | Homo sapiens |
79.9 | - |
unfolding temperature of enzyme hAPRT with PRPP and adenine | Homo sapiens |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7.5 | - |
assay at | Homo sapiens |
General Information | Comment | Organism |
---|---|---|
metabolism | the reversible adenine phosphoribosyltransferase enzyme (APRT) is essential for purine homeostasis in prokaryotes and eukaryotes. In humans, APRT (hAPRT) is the only enzyme known to produce AMP in cells from dietary adenine. APRT can also process adenine analogues, which are involved in plant development or neuronal homeostasis | Homo sapiens |
additional information | analysis of the molecular mechanism underlying substrate specificity of APRT and catalysis in both directions of the reaction. Comparison of the crystal structures of hAPRT complexed to three cellular nucleotide analogues (hypoxanthine, IMP, and GMP) with the phosphate-bound enzyme. Substrate shape recognition in the forward reaction, purine base recognition in the reverse reaction. Binding to hAPRT is substrate shape-specific in the forward reaction, whereas it is base-specific in the reverse reaction. Quantum mechanics/molecular mechanics (QM/MM) analysis suggests that the forward reaction is mainly a nucleophilic substitution of type 2 (SN2) with a mix of SN1-type molecular mechanism. Based on our structural analysis, a magnesium-assisted SN2-type mechanism is involved in the reverse reaction. Structure-function analysis, overview | Homo sapiens |