Phytase hydrolysis

RAPP c, LANTZSCH H J, DROCHNER w (2001) Hydrolysis of ph)dic acid hy intrinsic plant and supplemented microbial phytase Aspergillus niger) in the stomach and small intestine of minipigs fitted with re-entrant cannnlas. 3. Hydrolysis of ph)dic acid (1P6) and occurrence of hydrolysis products (1P5,1P4, 1P3 and 1P2). JAnim Physiol Anim Nutr (Berl). 85 420-30. 

Oxidation by raising the pH (to 7.5) phytase activity is switched off hydrolysis is prevented. Oxidation of L-glycerol-3-phosphate to DHAP by GPO at 55% glycerol (v/v) is quantitative. Catalase is added to suppress the build-up of hydrogen peroxide. The D-isomer is converted back into glycerol and phosphate in the last step. 

This enzyme [EC 3.1.3.26], also known as phytase, phy-tate 6-phosphatase, and myo-inositol-hexaphosphate 6-phosphohydrolase, catalyzes the hydrolysis of myoinositol hexakisphosphate to produce 1-myo-inositol... 

Lemaire et al. have developed a efficient fructose-1,6-bisphosphate aldolase (FBPA)-mediated synthesis of aminocyclitol analogs of valiolamine [34], This one-pot route involves the formation of two C—C bonds where four stereocenters are created. The first C—C bond formation reaction is catalyzed by the aldolase, coupling DHAP to nitrobutyraldehydes the other one is the result of a highly stereoselective intramolecular Henry reaction occurring on the intermediate nitroketone under acidic conditions during the aldolase-catalyzed reaction and phytase-catalyzed phosphate hydrolysis coupled step (Scheme 4.13). 

In a first exploration [19], starting from 9, the linear ketose usually obtained after aldol condensation was never obtained the nitromethylene reacted instantaneously with the ketone to give nitrocyclitol 11 in a highly stereoselective process. Only one major isomer was isolated after hydrolysis of the phosphate with phytase (Figure 18.5). 

Phytate hydrolysis into inositol and phassphate (feed) Phytase... 

In soybean concentrates and isolates much of the phytate remains associated with the protein in fact, phytate may constitute as much as 2-3% of the weight of a commercial protein isolate (57). A low-phytate soybean protein isolate can be prepared from soybean flour, however, by allowing endogenous phytase to act on the phytate in a 6% suspension of the flour at pH 5 at a temperature of 65°C (58). Hydrolysis of the phytate facilitates its separation from the bulk of the soybean protein which is then concentrated by ultrafiltration using a membrane which is permeable to phytate and its hydrolysis products but impermeable to protein. The product obtained by this method contains over 90% protein and only about 0.3% phosphorus. 

Activation energy values for the hydrolysis of myo-inositol hexakisphosphate and of esters with lower phosphate content were between 35.6 kJ/mol in germinated Phaseolus aureus (Mandal et al., 1972) and 50.2 kJ/mol in wheat bran (Nagai and Funahashi, 1962). The optimum temperature for the enzymatic hydrolysis of myo-inositol hexakisphosphate varies among phytases between 45 and 57°C (Nayini and Markakis, 1986), and even up to 60°C for the phytase of Bacillus subtilis (Powar and Jagannathan, 1982). 

The lowest and the highest values for myo-inositol hexakisphosphate hydrolysis were reported in phytases of Aspergillus ficuum (pH 5.3, 0.01 mM) and in that of germinated Phaseolus aureus (0.65 mM), respectively. The highest values reported were of wheat bran phytase towards myoinositol tetrakis- and trisphosphate (5 mM see Nayini and Markakis, 1986). K and K, values for the enzymatic hydrolysis of myoinositol hexakisphosphate by different Bacillus spp. were determined to be approximately 0.44 mM and 18.6/s, respectively. The affinity of myo-inositol pentakisphosphate for the phytase enzymes and their maximal rates of hydrolysis were lower (K = 0.50-0.76 mM 7.4-16/s) than that of myo-inositol hexakisphosphate (Greiner et al., 2002). 

The classical method of measuring phosphatase activity by the hydrolysis of para-nitrophenyl phosphate could be irrelevant for estimating the potential hydrolysis of natural organic phosphorus compounds such as myo-inositol hexakisphosphate, since the relative activity of phytase compared to para-nitrophenyl phosphatase activity may be several orders of magnitude lower (Beck et al., 1989 Joner et al., 2000 Tib-bett, 2002). 

Finally, phosphorus availabilities for feed materials are only partially additive, due to the curvilinear response of hydrolysis of phytate phosphorus to increasing phytase supplementation. In addition, plant phytase activity only corresponds to 60% of that of microbial phytase. A solution to these problems could be to estimate phosphorus availability by considering, firstly, the non-phytate phosphorus and secondly, by estimating the proportion of phytate hydrolysed from total phytate phosphorus and from phytase activity in the diet after heat treatment. 

Various dermatan sulfate derived di-, tetra-, hexa-, octa-, deca- and dodeca-saccharide mixtures have been prepared and purified (on a semi-preparative scale) by controlled depolymerization of dermatan sulfate using chondroitin ABC lyase, The pathways of InsPe hydrolysis by phytase from wheat bran of Triticum aestivum have recently been established. ... 

Oxidation. By raising the pH to 7.5, phytase activity is "switched off" and hydrolysis is prevented. Oxidation of 1-glycerol... 

Dephosphorylation. Lowering the pH back to 4 "switches on" phytase s activity, and hydrolysis of the aldol adduct is initiated. 

The catabolites of phytase activity in wheat are myo-inositol, phosphate, and the macroelements potassium, magnesium and calcium. Myo-inositol phosphate ester intermediates with fewer than six phosphate groups do not accumulate within the grain during hydrolysis of the phytin molecule [94], which is indicative of its rapid and complete breakdown by phytases. Movement of the catabolites from the aleurone layer and their redistribution into the developing seedling appears to be by simple diffusion through the endosperm, without any apparent competition for uptake by the scutellum. 

Kerovuo J, Tynkkynen S (2000) Expression of Bacillus subtilis phytasem Lactobacillus plantarum 755. Lett Appl Microbiol 30 325-329 Kerovuo J, Rouvinen J, Hatzack F (2000) Analysis of myo-inositol hexakisphosphate hydrolysis by bacillus phytase. indication of a novel reaction mechanism. Biochem J 352 623-628 Kitahata S, Taniguchi M, Beltran SD, Sugimoto T, Okada S (1983) Purification and some properties of cyclodextrinase from Bacillus coagulans. Agric Biol Chem 47 1441-1447... 

Park SC, Choi YW, Oh TK (1999) Comparative enzymatic hydrolysis of phytate in various animal feedstuff with two different phytases. J Vet Med Sci 61 ... 

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