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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down 12/28 - 12/31
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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down 12/28 - 12/31
for maintenance.
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MetaCyc Enzyme: phytase / 4-phytase

Synonyms: LP2

Species: Lupinus luteus

Summary:
A phytase was purified from germinated 4-day-old Lupinus albus seedlings [Greiner02]. This monomeric enzyme was shown to dephosphorylate phytate at position 4, thereby producing Ins(1,2,3,5,6)P5 [Greiner02a]. Like many phytases, the enzyme displays substrate inhibition at phytate concentrations >8 mmol.L-1 [Greiner02]. The enzyme has a pH optimum of 5.0. The purified enzyme is stable over a 3.5-7.5 pH-range but is virtually inactive below pH 3.0 and above pH 8.0 [Greiner02]. Fe2+ and Fe3+ were shown to reduce phytase activity. This effect was attributed to a lowering of phytate concentrations due to appearance of an iron phytate precipitate [Greiner02]. The enzyme is not a metalloenzyme.

Molecular Weight of Polypeptide: 65 kD (experimental) [Greiner02 ]

Gene-Reaction Schematic: ?


Enzymatic reaction of: myo-inositol-biphosphate phosphohydrolase (phytase / 4-phytase)

D-myo-inositol (1,2) bisphosphate + H2O <=> 1D-myo-inositol 2-monophosphate + phosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: phytate degradation I


Enzymatic reaction of: myo-inositol-triphosphate phosphohydrolase (phytase / 4-phytase)

D-myo-inositol (1,2,6) trisphosphate + H2O <=> D-myo-inositol (1,2) bisphosphate + phosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: phytate degradation I


Enzymatic reaction of: myo-inositol-tetrakisphosphate phosphohydrolase (phytase / 4-phytase)

D-myo-inositol (1,2,5,6) tetrakisphosphate + H2O <=> D-myo-inositol (1,2,6) trisphosphate + phosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: phytate degradation I


Enzymatic reaction of: myo-inositol-pentakisphosphate phosphohydrolase (phytase / 4-phytase)

D-myo-inositol (1,2,3,5,6) pentakisphosphate + H2O <=> D-myo-inositol (1,2,5,6) tetrakisphosphate + phosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: phytate degradation I


Enzymatic reaction of: myo-inositol-hexakisphosphate 4-phosphohydrolase (phytase / 4-phytase)

EC Number: 3.1.3.26

1D-myo-inositol 1,2,3,4,5,6-hexakisphosphate + H2O <=> D-myo-inositol (1,2,3,5,6) pentakisphosphate + phosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

In Pathways: phytate degradation I

Summary:
The Km and Kcat for the hydrolysis of sodium phytate at pH = 5.0 and 35?C were determined to be 130 μmol and 533 s-1, respectively.

Inhibitors (Other): Fe2+ [Greiner02] , Fe3+ [Greiner02]

Inhibitors (Unknown Mechanism): fluoride [Greiner02] , phosphate [Greiner02] , molybdate [Greiner02] , tungstate [Greiner02] , vanadate [Greiner02] , Cu2+ [Greiner02] , Zn2+ [Greiner02]

Primary Physiological Regulators of Enzyme Activity: phosphate

Kinetic Parameters:

Substrate
Km (μM)
Citations
1D-myo-inositol 1,2,3,4,5,6-hexakisphosphate
130.0
[Greiner02]

T(opt): 50 °C [Greiner02]

pH(opt): 5 [Greiner02]


References

Greiner02: Greiner R (2002). "Purification and characterization of three phytases from germinated lupine seeds (Lupinus albus var. amiga)." J Agric Food Chem 50(23);6858-64. PMID: 12405788

Greiner02a: Greiner R, Larsson Alminger M, Carlsson NG, Muzquiz M, Burbano C, Cuadrado C, Pedrosa MM, Goyoaga C (2002). "Pathway of dephosphorylation of myo-inositol hexakisphosphate by phytases of legume seeds." J Agric Food Chem 50(23);6865-70. PMID: 12405789


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Fri Dec 19, 2014, BIOCYC14A.