Acetyl Phosphate Formation in the Phosphorolytic Cleavage of Pentose Phosphate

Heath, Edward C.; Hurwitz, Jerard; Horecker, B.L.

doi:10.1021/ja01601a081

Cited by 46 publications

(24 citation statements)

References 3 publications

(4 reference statements)

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“…no. Of the established routes of ethanol formation (Dawes, 1963) only phosphoketolase cleavage of pentose phosphate (Heath, Hurwitz & Horecker, 1956) could also explain the labelling pattern observed and this enzyme was not detected. Further, the 6-phosphogluconate dehydrogenase of Z. anaerobia is only weakly active, specific for NADP and, in the shown absence of NAD-NADPH transhydrogenase, could not couple with the NADspecific ethanol dehydrogenase.…”

Section: Resultsmentioning

confidence: 84%

Glucose and fructose metabolism in Zymomonas anaerobia

Mcgill

Dawes

1971

Biochemical Journal

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Isotopic and enzymic evidence indicates that Zymomonas anaerobia ferments glucose via the Entner-Doudoroff pathway. The molar growth yields with glucose (5.89) and fructose (5.0) are lower than those for the related organism Zymomonacs mobilis and the observed linear growth suggests that energetically uncoupled growth occurs. A survey of enzymes of carbohydrate metabolism revealed the presence of weak phosphofructokinase and fructose 1,6-diphosphate aldolase activities but phosphoketolase, transketolase and transaldolase were not detected. Fermentation balances for glucose and fructose are reported; acetaldehyde accumulated in both fermentations, to a greater extent with fructose which also yielded glycerol and dihydroxyacetone as minor products.

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Section: Resultsmentioning

confidence: 84%

Glucose and fructose metabolism in Zymomonas anaerobia

Mcgill

Dawes

1971

Biochemical Journal

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“…D-Xylulose may undergo phosphorolysis to acetyl phosphate and triose phosphate (23). D-Arabinose may be catabolized by the following scheme (24): D-arabinose--D-arabonic acid-*2 keto, 3-deoxyarabonic acid--pyruvic acid plus glycolic acid.…”

Section: Discussionmentioning

confidence: 99%

The Metabolic Fate of C14 Labeled Pentoses in Man

Segal¹,

Foley²

1959

J. Clin. Invest.

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The role of pentoses in intermediary metabolism has received much attention within the past few years. The phosphate esters of D-ribose, D-ribulose and D-xylulose have been identified as key intermediates in the pentose phosphate pathway of glucose metabolism in both plant and mammalian tissue (1). More recently, another alternate pathway of glucose dissimilation, the uronic acid pathway, has been described in which L-Xylulose, xylitol and D-xylulose are intermediates (2).Several pentoses have been identified in normal urine: the aldopentoses xylose, arabinose and ribose (3, 4) and the ketopentoses D-ribulose and L-xylulose (5). Large quantities of the latter sugar are excreted in the disease essential pentosuria (6, 7), which appears to be due to a defect in the further conversion of L-xylulOse to the sugar alcohol xylitol (8). In addition to L-xylulOse Touster and Harwell (9) have also reported the isolation of L-arabitol from the urine of pentosuric subjects.Because of increasing awareness of the biological importance of the pentoses, certain aspects of pentose metabolism in man have been investigated in this laboratory. Previous reports have described the physiological disposition of large quantities of infused pentoses (10), the effect of insulin on blood levels of infused pentoses (11) as well as studies of the metabolism of D-ribose (12). This paper reports some observations on the fate of C14 labeled D-xylOse, D-lyxose, D-arabinose and L-arabinose administered in trace quantities intravenously to normal human subjects. Some of the previously published data (12) on C14 ribose metabolism are included for purposes of comparison. METHODSFive experiments were performed in four normal male volunteers aged 18 to 21. Each subject had been on a 250 Gm. carbohydrate diet for at least three days and was fasted overnight prior to study.Five /Ac. of each sugar dissolved in 250 ml. of normal saline were infused over a 15 minute period. Expired air samples were collected for 4 minutes at 15 to 60 minute intervals for 6 hours. Urine samples were collected at hourly intervals for 6 hours and pooled thereafter till 24 hours had elapsed from the start of the experiment. A urine sample was obtained at the twentyfifth hour to determine if C" was still being excreted. Urine was preserved by freezing at -20' C. Blood wvas collected at 20 minute intervals.Methods for the collection and C' counting of expired CO,, for preparation and radioactive assay of blood samples, and C' counting and chromatography of labeled compounds in urine have previously been described (12).The C" pentoses D-xylose, D-lyxose, D-arabinose, Larabinose and D-ribose (Figure 1) with specific activity of 0.67, 1.65, 1.65, 1.11, 2.6 and 2.01 ,lc. per mg., respec-H C=O H-C-OH

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“…The structure and mechanism of transketolase have been extensively studied, 121) but the three-dimensional structure and reaction mechanism of phosphoketolase has long been enigmatic, although phosphoketolase was discovered more than 50 years ago. [122][123][124] Very recently, crystallization of phosphoketolase from Lactococcus lactis 125) and structure determination of a substrate-free form of XFPK from B. longum JCM1217 126) were reported. Our group also succeeded in crystallization 127) and structure determination 128) of XFPK from B. breve (Fig.…”

Section: Bifid Shuntmentioning

confidence: 99%

Unique Sugar Metabolic Pathways of Bifidobacteria

Fushinobu

2010

Bioscience, Biotechnology, and Biochemistry

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Acetyl Phosphate Formation in the Phosphorolytic Cleavage of Pentose Phosphate

Cited by 46 publications

References 3 publications

Glucose and fructose metabolism in Zymomonas anaerobia

Glucose and fructose metabolism in Zymomonas anaerobia

The Metabolic Fate of C14 Labeled Pentoses in Man

Unique Sugar Metabolic Pathways of Bifidobacteria

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