Inositol hexaphosphate oxygenation

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. 

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)].

The observation by Chanutin and collaborators (CIO, S64) and by Benesch and Benesch (B25, B26) that 2,3-DPG (and also ATP and inositol hexaphosphate, or IHP) binds to hemoglobin resulting in a shift to the right of the oxygen dissociation curve has led to numerous reports which describe topics related to biochemical and medical aspects of the... 

Inositol (hexahydroxycyclohexane) occurs in several isomeric forms. Myo-inositol (or meso-inositol) is an important constituent of phospholipids and is the only isomer with biological activity. Inositol hexaphosphate (phytic acid) is found in avian erythrocytes, where it binds to hemoglobin, thereby regulating the oxygen capacity of the blood. It is also important as an intracellular messenger in a number of pathways. 

Several multivalent anions, including inositol hexaphosphate (18), lower the oxygen affinity of haemoglobin. The crystal structure of the complex of... 

Other Effectors for Oxygen Release - The blood of birds contains inositol hexaphosphate (Figure... 

Inositol hexaphosphate is a component of the blood of birds that favors the release of oxygen from hemoglobin by a mechanism similar to that of 2,3-bisphosphoglycerate in other animals. 

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. 

---