Inositol hexaphosphate effects

G. R. Findenegg and J. A. Nelenians, The effect of phytase on the availability of P from myo-inositol hexaphosphate (phytate) for maize root. Plant Soil 754 189 (1993). 

Goodford PI, St-Louis J, Wootton R. A quantitative analysis of the effects of 2,3-diphosphoglycerate, adenosine triphosphate and inositol hexaphosphate on the oxygen dissociation curve of human haemoglobin. J Physiol 1978 283 397. 

We next turn to the effect of adding D-2,3-bisphosphoglycerate (BPG, previously known as DPG) and inositol hexaphosphate (IHP). 

Figure 4. Effect of pH on the 31P FT-NMR spectrum of inositol hexaphosphate in a concentrated humic-FeEDTA matrix.

Fig. 23. Effects of inositol hexaphosphate and oxygenation on the linewidth of the hyperfine-shifted proton resonances of —12% Hb A in 0.1 Af Bis-Tris in D20 at pH 6.6 and 27°C. (A) 31.6% oxygenadon (—) (same as spectrum C of Fig. 22) (B) 31.6% oxygenation in the presence of 1 ImAf IHP (—) (C) 48% oxygenation in the presence of 11 mAf IHP (—). The intensities of the 18-ppm resonance in spectra B and C have been prescaled to give the same intensity as that of the 18-ppm peak in spectrum A. [From Viggiano et al. (1979)].

Tantivejkul, K., Vucenik, I., Eiseman, J., and Shamsuddin, A.M., 2003, Inositol hexaphosphate (IP6) enhances the anti-proliferative effects of adriamycin and tamoxifen in breast cancer. Breast Cancer Res. Treat. 79 301-312. 

Anderson, G. (1963) Effect of iron/phosphorus ratio and acid concentration on the precipitation of ferric inositol hexaphosphate. youma/ of the Science of Food and Agriculture 14,... 

Celi, L., Presta, M., Ajmone-Marsan, F. and Barberis, E. (2001) Effects of pH and electrolyte on inositol hexaphosphate interaction with goethite. Soil Science Society of America Journal 65, 753-760. 

Gray RD, Gibson QH (1971) The effect of inositol hexaphosphate on the kinetics of CO and O2 binding by human hemoglobin. J Biol Chem 246 7168-7174... 

Certain ions, e.g., oxalate and phosphate, can bind Ca within the intestinal canal and high intake of phosphate can restrict calcium absorption. A similar effect is encountered by phytic acid (inositol hexaphosphate) that is present in high amounts in certain cereals. Disturbances in the fat absorption (dietary) decreases the calcium absorption because Ca is bound to nonabsorbable fatty acids. 

Recently, the determination of phytic acid (myo-inositol hexaphosphate), which is believed to have an effect on the bioavailability of mineral substances, has become important. While phytic acid is not a food conshtuent in the United States, in other countries it is frequently added to foods as an anhoxidant [250,... 

Certain foods such as unrefined cereals and sugar cane juice contain organic phosphates, e.g. phytate (inositol hexaphosphate), which reduce enamel solubility, apparently by reacting with calcium phosphate salts on the enamel surface. The view that this type of compound has a caries-inhibiting effect is supported by observations that dietary supplements of calcium glycerophosphate reduce caries in rats and monkeys. At the same time, the calcium-binding properties of phytate may adversely affect the absorption of calcium from the intestine (page 143). 

The structure of horse metHb has been determined at 2.0 A resolution. The increased resolution (c/. 5.5 and 2.8 A) is sufficient to show up a number of bound water molecules in the contact regions between the subunits which had been overlooked previously, but it is not, unfortunately, sufficient to decide whether the porphyrin rings are fiat or slightly domed, puckered or ruffled. The effects of pressure on the visible spectra of metHb and metMb have been reported (together with those of cytochrome c and horse radish peroxidase) the effect is to shift the equilibrium between open and closed crevice structures in favour of the latter. The spectrum of the short-lived intermediate formed in the reaction of eaq" with metHb is consistent with a low-spin iron(ii) species the rate of its subsequent transition to the stable high-spin derivative is solvent dependent. The results of a resonance Raman study on inositol hexaphosphate binding to metHb fluoride are consistent... 

Kinetic studies have revealed that the inhibition of enzyme activities by humic s >stances can be competitive, non-competitive or a mixture of both. An example of competitive inhibition was shown for phytase using 777 inositol hexaphosphate as the substrate. In this case the inhibition was caused by the formation of a complex between HA and the substrate thus effectively lowering the availability of the s >strate to... 

Calcium is not always available in sufficient amounts from the diet because it is usually absorbed incompletely. Absorbability of dietary Ca++ depends greatly on the other food components. Oxalate and phytin (inositol hexaphosphate), in particular, impede the absorption in the small intestines by forming slightly soluble salts. Citrate, on the other hand, enhances the availability of Ca++, probably by forming soluble complex salts. Lastly, vitamin D greatly improves the absorbability of Ca++ the value of the vitamin in treating rickets is based, at least in part, on this effect. 

Certain substances have been found that are more powerful allosteric effectors than those that occur naturally some of these may eventually become medically useful. Inositol hexaphosphate (IHP) is a compound similar to DPG it binds at the same site as DPG in the T quaternary structure [74A], but it has a greater effect on oxygen affinity because it binds more tightly. Recently, certain chlorobenzene compounds have been found to be potent allosteric effectors [86P, 88L, 90L1]. These reduce oxygen affinity by binding preferentially to the T structure. Their binding sites are in the central cavity near the centre of the molecule. 

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