Abstract
The carbohydrate metabolism of the autotrophically grown blue-green alga, Tolypothrix tenuis, was studied. The alga respires glucose, fructose, galactose, and ribose.
About 60% of the glucose consumed is converted by starved cells into a glucose polysaccharide. Glucose uptake and O2 consumption are not inhibited by 0.01 m arsenite or by 0.005 m iodoacetamide.
The distribution of 14C in the polysaccharide glucose was established after feeding of glucose-1-14C, -2-14C, -6-14C, ribose-1-14C, and fructose-6-14C. Randomization of isotope between the 2 halves of the glucose from polysaccharide is limited when the experiments are carried out in the dark. After an extended incubation glucose-2-14C yields a glucose molecule with isotope labeled approximately equal in C-1, C-2 and C-3.
When the labeled glucoses were fed at a light intensity of compensation point, and in the presence of carbon dioxide, a greater degree of randomization of isotope occurred. The enhanced randomization of isotope is thought to result from an additional supply of triose phosphates as a result of photosynthesis which creates an environment favorable to the reversal of the glycolytic reactions.
To account for the labeling patterns and the resistance of respiration to the inhibitors, it is proposed that the oxidative pentose phosphate cycle is the major pathway of carbohydrate breakdown in this alga.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- DICKENS F., GLOCK G. E. Direct oxidation of glucose-6-phosphate, 6-phosphogluconate and pentose-5-phosphates by enzymes of animal origin. Biochem J. 1951 Nov;50(1):81–95. doi: 10.1042/bj0500081. [DOI] [PMC free article] [PubMed] [Google Scholar]
- GIBBS M., HORECKER B. L. The mechanism of pentose phosphate conversion to hexose monophosphate. II. With pea leaf and pea root preparations. J Biol Chem. 1954 Jun;208(2):813–820. [PubMed] [Google Scholar]
- Gibbs M., Kandler O. ASYMMETRIC DISTRIBUTION OF C IN SUGARS FORMED DURING PHOTOSYNTHESIS. Proc Natl Acad Sci U S A. 1957 Jun 15;43(6):446–451. doi: 10.1073/pnas.43.6.446. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gibbs M. The Respiration of the Pea Plant. Oxidation of Hexose Phosphate and Pentose Phosphate by Cell-free Extracts of Pea Leaves. Plant Physiol. 1954 Jan;29(1):34–39. doi: 10.1104/pp.29.1.34. [DOI] [PMC free article] [PubMed] [Google Scholar]
- KANDLER O., GIBBS M. Untersuchungen über den Einfluss der Photosynthese auf die Austauschvorgänge innerhalb des Hexosemoleküls. Z Naturforsch B. 1959 Jan;14B(1):8–13. [PubMed] [Google Scholar]
- KINDEL P., GIBBS M. DISTRIBUTION OF CARBON-14 IN POLYSACCHARIDE AFTER PHOTOSYNTHESIS IN CARBON DIOXIDE LABELLED WITH CARBON-14 BY ANACYSTIS NIDULANS. Nature. 1963 Oct 19;200:260–261. doi: 10.1038/200260a0. [DOI] [PubMed] [Google Scholar]
- Kratz W. A., Myers J. Photosynthesis and Respiration of Three Blue-Green Algae. Plant Physiol. 1955 May;30(3):275–280. doi: 10.1104/pp.30.3.275. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LJUNGDAHL L., WOOD H. G., RACKER E., COURI D. Formation of unequally labeled fructose 6-phosphate by an exchange reaction catalyzed by transaldolase. J Biol Chem. 1961 Jun;236:1622–1625. [PubMed] [Google Scholar]
- WOOD H. G., SCHAMBYE P., PEETERS G. J. Lactose synthesis. II. The distribution of C14 in lactose of milk from the perfused isolated cow udder. J Biol Chem. 1957 Jun;226(2):1023–1034. [PubMed] [Google Scholar]
- Willard J. M., Schulman M., Gibbs M. Aldolase in Anacystis nidulans and Rhodopseudomonas spheroides. Nature. 1965 Apr 10;206(980):195–195. doi: 10.1038/206195a0. [DOI] [PubMed] [Google Scholar]