The Labeling of Pentose Phosphate from Glucose-<sup>14</sup>C and Estimation of the Rates of Transaldolase, Transketolase, the Contribution of the Pentose Cycle, and Ribose Phosphate Synthesis<sup>*</sup>

Katz, Joseph; Rognstad, Robert

doi:10.1021/bi00859a046

Cited by 127 publications

(74 citation statements)

References 13 publications

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“…We propose that increased GK in Px islets elevates glucose 6-phosphate, which promotes PPP and entry of pyruvate into the TCA cycle; thus more protein, DNA, and pyruvate are synthesized. Increasing PPP activity produces more ribose phosphate that is used for DNA and RNA synthesis (19,51). We have shown that PPP activity and DNA synthesis were significantly increased in Px islets (28).…”

Section: Pc Pathway and Pyruvate Metabolism In Px Isletsmentioning

confidence: 84%

Enhanced rat β-cell proliferation in 60% pancreatectomized islets by increased glucose metabolic flux through pyruvate carboxylase pathway

Liu¹,

Han²,

Epstein³

et al. 2005

American Journal of Physiology-Endocrinology and Metabolism

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Section: Pc Pathway and Pyruvate Metabolism In Px Isletsmentioning

confidence: 84%

Enhanced rat β-cell proliferation in 60% pancreatectomized islets by increased glucose metabolic flux through pyruvate carboxylase pathway

Liu¹,

Han²,

Epstein³

et al. 2005

American Journal of Physiology-Endocrinology and Metabolism

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“…At the entry gate, D-glucose-6-phosphate is converted to D-glucono-lactone-6-phosphate by Zwf (44), which is metabolized to D-glycraldehyde-3-phosphate by a set of enzymes, Pgl, Gnd, RpiAB, and TktAB, for reuse in central metabolism (15,21).…”

Section: Discussionmentioning

confidence: 99%

Novel Members of the Cra Regulon Involved in Carbon Metabolism in Escherichia coli

2011

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Cra (catabolite repressor activator) is a global regulator of the genes for carbon metabolism in Escherichia coli. To gain insights into the regulatory roles of Cra, attempts were made to identify the whole set of regulation targets using an improved genomic SELEX (systematic evolution of ligands by exponential enrichment) system. Surprisingly, a total of 164 binding sites were identified for Cra, 144 (88%) of which were newly identified. The majority of known targets were included in the SELEX chip pattern. The promoters examined by the lacZ reporter assay in vivo were all regulated by Cra. These two lines of evidence indicate that a total of as many as 178 promoters are under the control of Cra. The majority of Cra targets are the genes coding for the enzymes involved in central carbon metabolism, covering all the genes for the enzymes involved in glycolysis and metabolism downstream of glycolysis, including the tricarboxylic acid (TCA) cycle and aerobic respiration. Taken together, we propose that Cra plays a key role in balancing the levels of the enzymes for carbon metabolism.Central carbon metabolism consists of three major pathways, the glycolysis (Embden-Meyerhof-Parnas [EMP]) pathway, the pentose-phosphate (PP) pathway, and the tricarboxylic acid (TCA) cycle, altogether leading to the production of metabolic energy. These three pathways also provide a number of building blocks that are utilized for the construction of cell architecture (for reviews, see references 26, 43, and 50).

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“…The problem of the determination ofthe quantitative participation of the different metabolic pathways in glucose breakdown by using specifically labelled substrates has frequently been discussed (see, e.g., Wood, Katz & Landau, 1963;Katz & Rognstad, 1967). The uniqueness ofthe metabolism of Rh.…”

Section: Discussionmentioning

confidence: 99%

Importance of the pentose phosphate pathway for d-glucose catabolism in the obligatory aerobic yeast Rhodotorula gracilis

Höfer¹,

Brand²,

Deckner³

et al. 1971

Biochemical Journal

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u-Glucose catabolism of a phosphofructokinase-deficient yeast Rhodotorula gracilis has been studied. By using D-glucose specifically 14C-labelled at different positions and measuring the distribution of the label in various fractions of cell metabolism, the following results were found. 1. The pentose phosphate pathway, being the main pathway of D-glucose catabolism, simultaneously converts glucose molecules into pentose phosphates oxidatively by using two NADP-linked dehydrogenases and via the non-oxidative transketolase-transaldolase pathway.2. From the correlation of the '4CO2 liberation and the D-glucose consumption and from the fact that the pentose phosphate moiety in nucleic acids is almost equally labelled from D-[1-14C]-and D-[6-_4C]-glucose, it is concluded that of the glucose utilized about 80% undergoes transformation via the non-oxidative pentose phosphate pathway. Only about 20% of glucose is directly decarboxylated to pentose phosphate. 3. For further degradation it is postulated that the pentose phosphates are split into C2 fragments and glyceraldehyde 3-phosphates. 4. All three loci of oxidative decarboxylation appear to be effective in Rh. gracili., the oxidative part of the pentose phosphate pathway, the decarboxylation of pyruvate in the later part of the glycolytic pathway as well as the oxidation in the tricarboxylic acid cycle. 5. D-Glucose molecules taken up are only partially oxidized to C02: about four-fifths of each glucose molecule metabolized is incorporated into cell constituents. 6. The quantitative interrelations of the flUXes of D-glucose subunits along the catabolic pathways have been estimated and are discussed.

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The Labeling of Pentose Phosphate from Glucose-¹⁴C and Estimation of the Rates of Transaldolase, Transketolase, the Contribution of the Pentose Cycle, and Ribose Phosphate Synthesis^*

Cited by 127 publications

References 13 publications

Enhanced rat β-cell proliferation in 60% pancreatectomized islets by increased glucose metabolic flux through pyruvate carboxylase pathway

Enhanced rat β-cell proliferation in 60% pancreatectomized islets by increased glucose metabolic flux through pyruvate carboxylase pathway

Novel Members of the Cra Regulon Involved in Carbon Metabolism in Escherichia coli

Importance of the pentose phosphate pathway for d-glucose catabolism in the obligatory aerobic yeast Rhodotorula gracilis

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The Labeling of Pentose Phosphate from Glucose-14C and Estimation of the Rates of Transaldolase, Transketolase, the Contribution of the Pentose Cycle, and Ribose Phosphate Synthesis*

Cited by 127 publications

References 13 publications

Enhanced rat β-cell proliferation in 60% pancreatectomized islets by increased glucose metabolic flux through pyruvate carboxylase pathway

Enhanced rat β-cell proliferation in 60% pancreatectomized islets by increased glucose metabolic flux through pyruvate carboxylase pathway

Novel Members of the Cra Regulon Involved in Carbon Metabolism in Escherichia coli

Importance of the pentose phosphate pathway for d-glucose catabolism in the obligatory aerobic yeast Rhodotorula gracilis

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The Labeling of Pentose Phosphate from Glucose-¹⁴C and Estimation of the Rates of Transaldolase, Transketolase, the Contribution of the Pentose Cycle, and Ribose Phosphate Synthesis^*