Hydrolases;
Acting on ester bonds;
Phosphoric-monoester hydrolases
BRITE hierarchy

myo-inositol-hexakisphosphate phosphohydrolase

(1) myo-inositol hexakisphosphate + H2O = 1D-myo-inositol 1,2,4,5,6-pentakisphosphate + phosphate [RN:R03371];
(2) 1D-myo-inositol 1,2,4,5,6-pentakisphosphate + H2O = 1D-myo-inositol 1,2,5,6-tetrakisphosphate + phosphate [RN:R13243];
(3) 1D-myo-inositol 1,2,5,6-tetrakisphosphate + H2O = 1D-myo-inositol 1,2,6-trisphosphate + phosphate [RN:R13244];
(4) 1D-myo-inositol 1,2,6-trisphosphate + H2O = 1D-myo-inositol 1,2-bisphosphate + phosphate [RN:R13245];
(5) 1D-myo-inositol 1,2-bisphosphate + H2O = 1D-myo-inositol 2-phosphate + phosphate [RN:R13246]

R03371 R13243 R13244 R13245 R13246;
(other) R03434
Reaction

myo-inositol hexakisphosphate [CPD:C01204];
H2O [CPD:C00001];
1D-myo-inositol 1,2,4,5,6-pentakisphosphate [CPD:C04563];
1D-myo-inositol 1,2,5,6-tetrakisphosphate [CPD:C22851];
1D-myo-inositol 1,2,6-trisphosphate [CPD:C22852];
1D-myo-inositol 1,2-bisphosphate [CPD:C22853]

This ubiquitous enzyme degrades myo-inositol hexakisphosphate (phytate) to Ins(2,3)P2 and Ins(2)P. Activities have been characterized in the yeast Saccharomyces cerevisiae [2], the plant Lupinus albus [3] and the bacteria Bacillus sp. [4] and Raoultella terrigena [5]. In mammal cells Ins(2,3)P2 and Ins(2)P are the major inositol phosphate compounds found [6]. The mammal enzyme is also active on Ins(1,3,4,5,6)P5 that is dephosphorylated to Ins(1,4,5,6)P4 and Ins(1,4,5)P3, and on 2,3-bisphospho-D-glycerate (cf. EC 3.1.3.80, 2,3-bisphosphoglycerate 3-phosphatase). In addition, it acts on Ins(1,3,4,5)P4 to yield Ins(1,4,5)P3 in vitro (cf. EC 3.1.3.67, phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase) [7]. It does not hydrolyse phosphates from the 2-positions of inositol phosphates [6]. In other organisms the degradation of phytate follows different routes. (cf. EC 3.1.3.8, 3-phytase, EC 3.1.3.26, 4-phytase, and EC 3.1.3.72, 5-phytase).

EC 3.1.3.62 created 1992, modified 2002, modified 2023

1  [PMID:9359836]

2  [PMID:11368581]

3  [PMID:12405789]

4  [PMID:12556126]

5  [PMID:16917535]

6  [PMID:36589890]

7  [PMID:37371464]