title: Inositol phosphate phosphatases of microbiological origin: the inositol pentaphosphate products of Aspergillus ficuum phytases.
abstract: The fungus Aspergillus ficuum NRRL 3135 is known to produce an extracellular nonspecific orthophosphoric monoester phosphohydrolase (EC 3.1.3.2) with a pH optimum of 2.0, as well as an extracellular myo-inositol hexaphosphate phosphohydrolase (EC 3.1.3.8; phytase) with pH optima of 2.0 and 5.5. Both these enzymes are also known to hydrolyze myo-inositol hexaphosphate. The pentaphosphates liberated in the first step of this hydrolysis have been isolated and identified by ion-exchange chromatography and optical rotation. The nonspecific orthophosphoric monoester phosphohydrolase produces a single pentaphosphate, d-myo-inositol-1,2,4,5,6-pentaphosphate, whereas the phytase, at both pH 2.0 and 5.5, produces a mixture of two pentaphosphates. The major component of this mixture is d-myo-inositol-1,2,4,5,6-pentaphosphate and the other is d-myo-inositol-1,2,3,4,5-pentaphosphate. Thus the pathways of dephosphorylation of myo-inositol hexaphosphate by these two enzymes differ from that of wheat-bran phytase which forms l-myo-inositol-1,2,3,4,5-pentaphosphate.
mesh_terms: D010832:6-Phytase / Q000378:metabolism*; D000135:Acid Phosphatase / Q000378:metabolism*; D001230:Aspergillus / Q000201:enzymology* / Q000378:metabolism; D002474:Cell-Free System; D055598:Chemical Phenomena; D002621:Chemistry; D002852:Chromatography, Ion Exchange; D003911:Dextrans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007294:Inositol; D009905:Optical Rotatory Dispersion; D010710:Phosphates / Q000032:analysis / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D003911:Dextrans; D010710:Phosphates; D007294:Inositol; D000135:Acid Phosphatase; D010832:6-Phytase