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. 1988 Mar;86(3):786–792. doi: 10.1104/pp.86.3.786

Enzyme Activities Associated with Maize Kernel Amyloplasts 1

Edgardo Echeverria 1, Charles D Boyer 1, Paul A Thomas 1, Kang-Chien Liu 1, Jack C Shannon 1
PMCID: PMC1054571  PMID: 16665989

Abstract

Activities of the enzymes of gluconeogenesis and of starch metabolism were measured in extracts of amyloplasts isolated from protoplasts derived from 14-day-old maize (Zea mays L., cv Pioneer 3780) endosperm. The enzymes triosephosphate isomerase, fructose-1,6-bisphosphate aldolase, fructose-1,6-bisphosphatase, phosphohexose isomerase, phosphoglucomutase, ADPG pyrophosphorylase, UDPG pyrophosphorylase, soluble and bound starch synthases, and branching enzyme were found to be present in the amyloplasts. Of the above enzymes, ADPG pyrophosphorylase had the lowest activity per amyloplast. Invertase, sucrose synthase and hexokinase were not detected in similar amyloplast preparations. Only a trace of the cytoplasmic marker enzyme alcohol dehydrogenase could be detected in purified amyloplast fractions. In separate experiments, purified amyloplasts were lysed and then supplied with radioactively labeled glucose-6-phosphate, glucose-1-phosphate, fructose-1,6-bisphosphate, dihydroxyacetone phosphate, glucose, fructose, sucrose, and 3-0-methylglucose in the presence of adenosine triphosphate or uridine triphosphate. Of the above, only the phosphorylated substrates were incorporated into starch. Incorporation into starch was higher with added uridine triphosphate than with adenosine triphosphate. Dihydroxyacetone phosphate was the preferred substrate for uptake by intact amyloplasts and incorporation into starch. In preliminary experiments, it appeared that glucose-6-P and fructose-1,6-bisphosphate may also be taken up by intact amyloplasts. However, the rate of uptake and incorporation into starch was relatively low and variable. Additional study is needed to determine conclusively whether hexose phosphates will cross intact amyloplast membranes. From these data, we conclude that: (a) Triose phosphate is the preferred substrate for uptake by intact amyloplasts. (b) Amyloplasts contain all enzymes necessary to convert triose phosphates into starch. (c) Sucrose breakdown must occur in the cytosol prior to carbohydrate transfer into the amyloplasts. (d) Under the conditions of assay, amyloplasts are unable to convert glucose or fructose to starch. (e) Uridine triphosphate may be the preferred nucleotide for conversion of hexose phosphates to starch at this stage of kernel development.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Cox E. L., Dickinson D. B. Hexokinase from maize endosperm and scutellum. Plant Physiol. 1973 May;51(5):960–966. doi: 10.1104/pp.51.5.960. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Dickinson D. B., Preiss J. ADP glucose pyrophosphorylase from maize endosperm. Arch Biochem Biophys. 1969 Mar;130(1):119–128. doi: 10.1016/0003-9861(69)90017-4. [DOI] [PubMed] [Google Scholar]
  3. Echeverria E., Boyer C., Liu K. C., Shannon J. Isolation of amyloplasts from developing maize endosperm. Plant Physiol. 1985 Mar;77(3):513–519. doi: 10.1104/pp.77.3.513. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Fliege R., Flügge U. I., Werdan K., Heldt H. W. Specific transport of inorganic phosphate, 3-phosphoglycerate and triosephosphates across the inner membrane of the envelope in spinach chloroplasts. Biochim Biophys Acta. 1978 May 10;502(2):232–247. doi: 10.1016/0005-2728(78)90045-2. [DOI] [PubMed] [Google Scholar]
  5. Hawker J. S., Ozbun J. L., Ozaki H., Greenberg E., Preiss J. Interaction of spinach leaf adenosine diphosphate glucose alpha-1,4-glucan alpha-4-glucosyl transferase and alpha-1,4-glucan, alpha-1,4-glucan-6-glycosyl transferase in synthesis of branched alpha-glucan. Arch Biochem Biophys. 1974 Feb;160(2):530–551. doi: 10.1016/0003-9861(74)90430-5. [DOI] [PubMed] [Google Scholar]
  6. Heldt H. W., Rapley L. Specific transport of inorganic phosphate, 3-phosphoglycerate and dihydroxyacetonephosphate, and of dicarboxylates across the inner membrane of spinach chloroplasts. FEBS Lett. 1970 Oct 5;10(3):143–148. doi: 10.1016/0014-5793(70)80438-0. [DOI] [PubMed] [Google Scholar]
  7. Jaynes T. A., Nelson O. E. An invertase inactivator in maize endosperm and factors affecting inactivation. Plant Physiol. 1971 May;47(5):629–634. doi: 10.1104/pp.47.5.629. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Journet E. P., Douce R. Enzymic capacities of purified cauliflower bud plastids for lipid synthesis and carbohydrate metabolism. Plant Physiol. 1985 Oct;79(2):458–467. doi: 10.1104/pp.79.2.458. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Liu T. T., Shannon J. C. Measurement of Metabolites Associated with Nonaqueously Isolated Starch Granules from Immature Zea mays L. Endosperm. Plant Physiol. 1981 Mar;67(3):525–529. doi: 10.1104/pp.67.3.525. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Miernyk J. A., Dennis D. T. Mitochondrial, plastid, and cytosolic isozymes of hexokinase from developing endosperm of Ricinus communis. Arch Biochem Biophys. 1983 Oct 15;226(2):458–468. doi: 10.1016/0003-9861(83)90315-6. [DOI] [PubMed] [Google Scholar]
  11. Murata T., Sugiyama T., Minamikawa T., Akazawa T. Enzymic mechanism of starch synthesis in ripening rice grains. 3. Mechanism of the sucrose-starch conversion. Arch Biochem Biophys. 1966 Jan;113(1):34–44. doi: 10.1016/0003-9861(66)90153-6. [DOI] [PubMed] [Google Scholar]
  12. Ozbun J. L., Hawker J. S., Preiss J. Adenosine diphosphoglucose-starch glucosyltransferases from developing kernels of waxy maize. Plant Physiol. 1971 Dec;48(6):765–769. doi: 10.1104/pp.48.6.765. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Pressey R. Potato sucrose synthetase: purification, properties, and changes in activity associated with maturation. Plant Physiol. 1969 May;44(5):759–764. doi: 10.1104/pp.44.5.759. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. RONGINEDEFEKETE M. A., CARDINI C. E. MECHANISM OF GLUCOSE TRANSFER FROM SUCROSE INTO THE STARCH GRANULE OF SWEET CORN. Arch Biochem Biophys. 1964 Jan;104:173–184. doi: 10.1016/s0003-9861(64)80052-7. [DOI] [PubMed] [Google Scholar]
  15. Schäfer G., Heber U. Glucose transport into spinach chloroplasts. Plant Physiol. 1977 Aug;60(2):286–289. doi: 10.1104/pp.60.2.286. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Simcox P. D., Reid E. E., Canvin D. T., Dennis D. T. Enzymes of the Glycolytic and Pentose Phosphate Pathways in Proplastids from the Developing Endosperm of Ricinus communis L. Plant Physiol. 1977 Jun;59(6):1128–1132. doi: 10.1104/pp.59.6.1128. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Thom M., Maretzki A. Group translocation as a mechanism for sucrose transfer into vacuoles from sugarcane cells. Proc Natl Acad Sci U S A. 1985 Jul;82(14):4697–4701. doi: 10.1073/pnas.82.14.4697. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Tsai C. Y., Salamini F., Nelson O. E. Enzymes of carbohydrate metabolism in the developing endosperm of maize. Plant Physiol. 1970 Aug;46(2):299–306. doi: 10.1104/pp.46.2.299. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Vallee B. L., Hoch F. L. ZINC, A COMPONENT OF YEAST ALCOHOL DEHYDROGENASE. Proc Natl Acad Sci U S A. 1955 Jun 15;41(6):327–338. doi: 10.1073/pnas.41.6.327. [DOI] [PMC free article] [PubMed] [Google Scholar]

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