Myo-Inositol tetrakisphosphate

This enzyme [EC 2.7.1.140], also referred to as iD-myo-inositol-tetrakisphosphate 5-kinase, catalyzes the reaction of ATP with iD-myo-inositol 1,3,4,6-tetrakisphos-phate to produce ADP and iD-myo-inositol 1,3,4,5,6-pentakisphosphate. 

ATP -I- 5-diphospho-lD-myo-inositol-pentakisphosphate = ADP -h bis(di-phospho)- D-myo-inositol tetrakisphosphate (isomeric configuration unknown)... 

Chemoenzymatic strategies were recently also applied for the preparative-scale synthesis of the very rare and expensive research biochemicals D-myo-inositol-l-phosphate, and D- and L-l,3,4,5-myo-inositol tetrakisphosphates [127,167]. The approach uses commercial lipase from Pseudomonas sp. for the regio- and enantioselective acetylation (in vinyl acetate) of 4,6-di-O-benzyl-myo-inositol to lD-l-acetoxy-4,6-di-0-benzyl-myo-inositol (intermediate for D-IP,). and lipase from Candida antarctica for the enantioseparation of racemic 2,6-dibenzyl-myo-inositol by enantioselective C5-acetylation (in the synthesis of D- and L-1,3,4,5-IP4) (Fig. 12). 

Example 62 commercially available diethylphosphorochloridite (EtO)2PCl has been used by Mills and Potter in the synthesis of myo-inositol 1,2,4,5-tetrakisphosphate [101]. 

This enzyme [EC 3.1.3.25], also referred to as myo-inosi-tol-l(or 4)-monophosphatase and myo-inositol-l-phos-phatase, catalyzes the hydrolysis of myo-inositol 1-monophosphate to generate myo-inositol and orthophosphate. Both enantiomers of myo-inositol 1-phosphate and myoinositol 4-phosphate can act as substrates. However, the enzyme does not hydrolyze inositol bisphosphates, tris-phosphates, or tetrakisphosphates. 

Inositol 1,3,4,5-tetrakisphosphate 3-phosphatase [EC 3.1.3.62] catalyzes the hydrolysis of D-myo-inositol... 

Inositol-1,4,5-trisphosphate 5-phosphatase [EC 3.1.3.56], also known as inositol trisphosphate phosphomonoester-ase and inositol polyphosphate 5-phosphatase, catalyzes the hydrolysis of D-myo-inositol 1,4,5-trisphosphate to produce D-myo-inositol 1,4-bisphosphate and orthophosphate. The type I enzyme (but not the type II enzyme) will also hydrolyze inositol 1,3,4,5-tetrakisphosphate at the 5-position. However, neither of the two... 

ID-myo-inositol 1,3,4,5-tetrakisphosphate <1> (<1> recombinant, catalytically active fragment of isoform C, allosteric product activation in the absence of Ca /calmodulin, which per se activates enzyme and abolishes the allosteric effect [31]) [31]... 

S ATP -I- D-myo-inositol 3,4,5,6-tetrakisphosphate <1-3, 5, 6, 7> (<1,2> i.e. L-myo-inositol 1,4,5,6-tetrakisphosphate, phosphorylation site l-3 or d-1 substitution position [2] <1,2> no activity with D-myo-inositol 1,3,4,5-tetrakisphosphate [2] <5> no activity with inositol-l,3,4,5-tetrakisphos-phate [6] <7> enzyme has both inositol-3,4,5,6-tetrakisphosphate 1-ki-nase and inositol-l,3,4-trisphosphate 5/6 kinase activity, 2 times higher activity than with inositol-1,3,4-trisphosphate, no activity with inositol-... 

Shears, S.B. The pathway of myo-inositol 1,3,4-trisphosphate phosphorylation in liver. Identification of myo-inositol 1,3,4-trisphosphate 6-kinase, myo-inositol 1,3,4-trisphosphate 5-kinase, and myo-inositol 1,3,4,6-tetrakisphosphate 5-kinase. J. Biol. Chem., 264, 19879-19886 (1989)... 

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