Hexosemonophosphate shunt

HI. Heller, P., Weinstein, H. G., West, M., and Zimmerman, H. J., Glycolytic, citric acid cycle and hexosemonophosphate shunt enzymes of plasma and erythrocytes in megaloblastic anemia. J. Lab. Clin. Med. 55, 425-434 (1900). 

K17. Kit, S., The role of the hexosemonophosphate shunt in tumors and lymphatic tissues. Cancer Research 10, 70-76 (1950). 

The actions of non-steroidal anti-inflammatory drugs appear to be diverse. Phenylbutazone and sulfmpyrzone inhibited several effects of FMLP on PMNs increased adhesiveness, stimulation of the hexosemonophosphate shunt, lysosomal enzyme release, and formation of O These effects were explained by the ability of both phenylbutazone and sulfinpyrazone to inhibit binding of labelled FMLP to PMNs. Both were selective in that neither inhibited responses of PMNs to Csa and neither inhibited the stimulation of the hexose monophosphate shunt by latex or by opsonized Candida. The responses of PMNs to FMLP, including the release of O have also been inhibited by 5,8,11,14 eicosatetraynoic acid, an inhibitor of the metabolism of arachidonic acid h by indomethacin and by... 

The metabolism of gluconate by L. casei has been shown by Buyze et al. (33) to be via the hexosemonophosphate shunt. L. casei was found to possess the enzyme 6-phosphogluconate dehydrogenase (6-PG) when this organism was grown with gluconate as the sole carbon source, the compoimd was metabolized through this pathway with the release of GO2. 

Glycolysis, the hexosemonophosphate shunt, and lipogenesis are prominent in fetal liver, whereas gluconeogenesis is essentially absent (Adam, 1971). The pattern is essentially reflected in the levels of specific enz3nnes involved in these pathways (Dawkins, 1966 Burch et al., 1963). The enzymes of amino acid catabolism and of the urea cycle are also low in the fetal liver. 

As for the biosynthesis of the pentoses, we have already shown that this can take place during the operation of the hexosemonophosphate shunt (p. 193) and we shall return to other aspects of this biosynthesis when we consider the formation of pentose phosphates (p. 253). 

As we have seen, D-ribose-5-phosphate is formed from G—6—P in the hexosemonophosphate shunt. 

It is only necessary to compare the pentose cycle of photosynthesis (Fig. 94) with the hexosemonophosphate shunt in Fig. 38 for their relationship to become apparent. Since the two mechanisms are still partly hypothetical, it is preferable to await further developments in our knowledge before attempting to establish a definite relation between respiration involving the hexosemonophosphate shunt and photosynthesis. The mode of formation of a triosephosphate molecule from three COg molecules is shown graphically in Fig. 95. 

Nevertheless, although the glycolytic cycle is firmly established as part of the metabolic mechanism, recent evidence strongly suggests that the hexosemonophosphate shunt plays an important role in the degradation of sugars in higher plants. 

It is not considered that the reactions described in this scheme (Fig. 23) present a complete picture of all the known reactions. Additional systems will be discussed below for the purposes of the discusrion immediately following, our attention will be focused on the systems of the scheme. The pathway involving glucose-6-phosphate dehydrogenase has been variously termed the oxidative pathway or the hexosemonophosphate shunt. 

Glycolysis Citric acid cycle -oxidation of fatty acids Hexosemonophosphate shunt Oxidative phosphorylation Fatty acid synthesis Pyrimidine synthesis Purine synthesis Amino acid activation Methylation and metabolism of single carbon compounds... 

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