Recherches sur la biochimie des cyclitols VIII. Sur la biosynthèse du méso‐inositol et du scyllitol chez le Rat

Posternak, Th.; Schöpfer, W. H.; Kaufmann-Boetsch, B.; Edwards, Susi

doi:10.1002/hlca.19630460726

Cited by 34 publications

(5 citation statements)

References 15 publications

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“…The scyllo-inositovmyo-inositol ratios found here resemble those reported for rabbit CNS (Sherman et al, 1968), both in magnitude and uniformity. The uniformity of these ratios within and across regions is consistent with a close metabolic interrelationship of these stereoisomers (Posternak et al, 1963;Sherman et al, 1968Sherman et al, , 1978Hipps et al, 1977).…”

Section: Comparisons With Other Studiessupporting

confidence: 73%

“…Finally, by use of the same analytical method, the ratio of scyllo-inositol t o myo-inositol was measured. scyllo-Inositol is metabolically related t o myo-inositol (Posternak et al, 1963), which it accompanies in many tissues (Sherman et al, 1968). An epimerase has been isolated from bovine brain that transforms rnyot o scyflo-inositol (Hipps e t al., 1977;Sherman et al, 1978).…”

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confidence: 99%

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Distribution of myo‐Inositol in the Cat Cochlear Nucleus

Godfrey

Hallcher

Laird

et al. 1982

Journal of Neurochemistry

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The distribution of myo-inositol, a substance that has been implicated in synaptic transmission, has been mapped within sections of the cat cochlear nucleus as well as some nearby regions. Highest values in the cochlear nucleus were found in regions of granule cells along the periphery of the anteroventral subdivision of the nucleus. Highest values overall were found in the molecular layer of the cerebellar flocculus. A fairly good correlation was found between myo-inositol levels and activities of the enzymes of acetylcholine metabolism in the cat cochlear nucleus, supporting the possibility that myo-inositol may be involved in cholinergic synaptic transmission. No positive correlation was found between myo-inositol levels and the levels of glutamate, aspartate, glycine, or gamma-aminobutyric acid (GABA). The most striking gradient of myo-inositol levels within a region was found in the auditory nerve, where different myo-inositol levels might be related to nerve fibers innervating different parts of the cochlea. The distribution of scyllo-inositol, a stereoisomer of myo-inositol, was also examined, and found to parallel closely the distribution of myo-inositol, with levels 4--5% as high.

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Section: Comparisons With Other Studiessupporting

confidence: 73%

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confidence: 99%

Distribution of myo‐Inositol in the Cat Cochlear Nucleus

Godfrey

Hallcher

Laird

et al. 1982

Journal of Neurochemistry

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“…Inososes have not been detected in tissue extracts to our knowledge, although the occurrence of scylloinosose can be inferred wherever jcyZZo-inositol is found (Posternak et al, 1959;Posternak, 1965;Kindi et al, 1966;Candy, 1967). Our earlier suggestion of the involvement of scyZZo-inosose in streptidine biosynthesis (Walker and Walker, 1966) has been given subsequent support by the experiments of Bruton et al (1967), which showed that .m^ZZo-inositol as Well as myoinositol can serve as a precursor of the streptidine moiety of streptomycin in vivo.…”

Section: Discussionmentioning

confidence: 74%

Enzymatic Synthesis of Streptidine from scyllo-Inosamine^*

Walker¹,

Walker²

1967

Biochemistry

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“…The same conversion is known to occur in higher plants [13] and in the rat [14], but the enzymic mechanisms have not yet been investigated. Other epimerizations in the cyclitol series which have been shown to take place are, for example, the formation of L-chiro-inositol in Artemisia species [15] and the epimerization of myo-inositol to D-chiro-inositol in green algae [16].…”

Section: Discussionmentioning

confidence: 99%

Enzymic Epimerization of Sequoyitol to d‐Pinitol in Trifolium incarnatum

Ruis

Hoffmann‐Ostenhof

1969

European Journal of Biochemistry

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The partial purification of an enzyme system from Trifoliurn incarnaturn catalyzing the epimerization of sequoyitol to D-pinitol and its characterization is described. The reaction proceeds via a keto intermediate, ~-5-O-methyl-Z,3,5/4,6-pentahydroxycyclohexanone, and is catalyzed by two dehydrogenases or one protein with two dehydrogenase actions, of which the first one is NAD-specific and oxidizes sequoyitol to the keto intermediate, whereas the other has the function to reduce the keto compound to D-pinitOl using NADPH as hydrogen donor. Both dehydrogenase actions as well as the overall epimerization reaction were shown to be reversible.Although the sequoyitol dehydrogenase activity can be easily destroyed by several means which leave the D-pinitol dehydrogenase activity intact, no real separation of the two activities has been achieved. The protein or proteins responsible for the two activities have a molecular weight of about 34,000 as determined by the gel filtration method.The two activities do not only differ in their sensitivity towards inhibitors, their substrate and coenzyme specificities, but also in their stereospecificity with respect to the coenzymes. Whereas the NAD-specific sequoyitol dehydrogenase activity is B-specific, the NADP-specific D-pinitOl dehydrogenase activity shows A-specificity. On the basis of these findings, a possible mechanism for the epimerization is discussed.The epimerization of sequoyitol t,o D-pinitOl is known to be the final step in the biosynthesis of the latter compound in Trifolium incarnatum [l]. Experiments in vivo with labelled precursors made it probable that this epimerization is taking place in two steps-an oxidation of sequoyitol to the keto compound, D -5 -0 -methyl -2,3,5/4,6 -pentahydroxycyclohexanone, followed by a reduction yielding D-phito1 (Scheme 1).

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Recherches sur la biochimie des cyclitols VIII. Sur la biosynthèse du méso‐inositol et du scyllitol chez le Rat

Cited by 34 publications

References 15 publications

Distribution of myo‐Inositol in the Cat Cochlear Nucleus

Distribution of myo‐Inositol in the Cat Cochlear Nucleus

Enzymatic Synthesis of Streptidine from scyllo-Inosamine^*

Enzymic Epimerization of Sequoyitol to d‐Pinitol in Trifolium incarnatum

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Recherches sur la biochimie des cyclitols VIII. Sur la biosynthèse du méso‐inositol et du scyllitol chez le Rat

Cited by 34 publications

References 15 publications

Distribution of myo‐Inositol in the Cat Cochlear Nucleus

Distribution of myo‐Inositol in the Cat Cochlear Nucleus

Enzymatic Synthesis of Streptidine from scyllo-Inosamine*

Enzymic Epimerization of Sequoyitol to d‐Pinitol in Trifolium incarnatum

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Product

Resources

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Enzymatic Synthesis of Streptidine from scyllo-Inosamine^*