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MetaCyc Enzyme: phytase / 3-phytase

Synonyms: LP11

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 3, thereby producing Ins(1,2,4,5,6)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: 56 kD (experimental) [Greiner02]

Gene-Reaction Schematic

Gene-Reaction Schematic


Enzymatic reaction of: myo-inositol-biphosphate phosphohydrolase (phytase / 3-phytase)

Inferred from experiment

D-myo-inositol (1,2) bisphosphate + H2O → 1D-myo-inositol 2-monophosphate + phosphate

The direction shown, i.e. which substrates are on the left and right sides, 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 / 3-phytase)

Inferred from experiment

D-myo-inositol (1,2,6) trisphosphate + H2O → D-myo-inositol (1,2) bisphosphate + phosphate

The direction shown, i.e. which substrates are on the left and right sides, 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 / 3-phytase)

Inferred from experiment

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

The direction shown, i.e. which substrates are on the left and right sides, 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 / 3-phytase)

Inferred from experiment

D-myo-inositol (1,2,4,5,6)-pentakisphosphate + H2O → D-myo-inositol (1,2,5,6) tetrakisphosphate + phosphate

The direction shown, i.e. which substrates are on the left and right sides, 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 3-phosphohydrolase (phytase / 3-phytase)

Inferred from experiment

EC Number: 3.1.3.8

phytate + H2O → D-myo-inositol (1,2,4,5,6)-pentakisphosphate + phosphate

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.

In Pathways: phytate degradation I

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
phytate 80.0 [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
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