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. 1993 Feb 1;289(Pt 3):777–782. doi: 10.1042/bj2890777

Direct desaturation of intact galactolipids by a desaturase solubilized from spinach (Spinacia oleracea) chloroplast envelopes.

H Schmidt 1, E Heinz 1
PMCID: PMC1132243  PMID: 8435075

Abstract

In plants, polyenoic fatty acids are synthesized by desaturase enzymes which use acyl groups of membrane lipids as substrates. To provide direct 'in vitro' evidence for this reaction, we solubilized envelope membranes from spinach (Spinacia oleracea) chloroplasts with Triton X-100 to release a membrane-bound n-6 desaturase. In the presence of oxygen and reduced ferredoxin, the solubilized enzyme desaturated a variety of substrates, such as free oleic acid, free erucic acid, 1-oleoyl-sn-glycerol 3-phosphate and the three galactolipids 1-oleoyl-2-(7'-cis-hexadecenoyl)-3-beta-D-galactopyranosyl-sn-glycerol, 1,2-dioleoyl-3-beta-D-galactopyranosyl-sn-glycerol and the ether analogue 1,2-di-(9'-cis-octadecenyl)-3-beta-D-galactopyranosyl-sn- glycerol. The in vitro desaturation of these exogenously added complex lipids with ester- and ether-linked substrate chains is unambiguous evidence for lipid-linked desaturation. The enzyme measures the insertion of the new double bond from the methyl end and the existing (n-9)-cis-double bond of an appropriate acyl or alkyl chain. The distal part of the substrate group, normally the carboxy end of a fatty acyl residue, is of less importance and, in particular, its activation in thioester form is not required.

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Selected References

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

  1. Andrews J., Schmidt H., Heinz E. Interference of electron transport inhibitors with desaturation of monogalactosyl diacylglycerol in intact chloroplasts. Arch Biochem Biophys. 1989 May 1;270(2):611–622. doi: 10.1016/0003-9861(89)90544-4. [DOI] [PubMed] [Google Scholar]
  2. Browse J., Kunst L., Anderson S., Hugly S., Somerville C. A mutant of Arabidopsis deficient in the chloroplast 16:1/18:1 desaturase. Plant Physiol. 1989 Jun;90(2):522–529. doi: 10.1104/pp.90.2.522. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Gurr M. I., Robinson M. P., James A. T. The mechanism of formation of polyunsaturated fatty acids by photosynthetic tissue. The tight coupling of oleate desaturation with phospholipid synthesis in Chlorella vulgaris. Eur J Biochem. 1969 May 1;9(1):70–78. doi: 10.1111/j.1432-1033.1969.tb00577.x. [DOI] [PubMed] [Google Scholar]
  4. Hajra A. K. On extraction of acyl and alkyl dihydroxyacetone phosphate from incubation mixtures. Lipids. 1974 Aug;9(8):502–505. doi: 10.1007/BF02532495. [DOI] [PubMed] [Google Scholar]
  5. Heinz E., Harwood J. L. Incorporation of carbon dioxide, acetate and sulphate into the glycerolipids of Vicia faba leaves. Hoppe Seylers Z Physiol Chem. 1977 Jul;358(7):897–908. doi: 10.1515/bchm2.1977.358.2.897. [DOI] [PubMed] [Google Scholar]
  6. Heinz E., Roughan P. G. Similarities and differences in lipid metabolism of chloroplasts isolated from 18:3 and 16:3 plants. Plant Physiol. 1983 Jun;72(2):273–279. doi: 10.1104/pp.72.2.273. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Jones A. V., Harwood J. L. Desaturation of linoleic acid from exogenous lipids by isolated chloroplasts. Biochem J. 1980 Sep 15;190(3):851–854. doi: 10.1042/bj1900851. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Kearns E. V., Hugly S., Somerville C. R. The role of cytochrome b5 in delta 12 desaturation of oleic acid by microsomes of safflower (Carthamus tinctorius L.). Arch Biochem Biophys. 1991 Feb 1;284(2):431–436. doi: 10.1016/0003-9861(91)90319-e. [DOI] [PubMed] [Google Scholar]
  9. Murphy D. J., Mukherjee K. D., Woodrow I. E. Functional association of a monoacylglycerophosphocholine acyltransferase and the oleoylglycerophosphocholine desaturase in microsomes from developing leaves. Eur J Biochem. 1984 Mar 1;139(2):373–379. doi: 10.1111/j.1432-1033.1984.tb08016.x. [DOI] [PubMed] [Google Scholar]
  10. Ohlrogge J. B., Browse J., Somerville C. R. The genetics of plant lipids. Biochim Biophys Acta. 1991 Feb 26;1082(1):1–26. doi: 10.1016/0005-2760(91)90294-r. [DOI] [PubMed] [Google Scholar]
  11. Okayasu T., Nagao M., Ishibashi T., Imai Y. Purification and partial characterization of linoleoyl-CoA desaturase from rat liver microsomes. Arch Biochem Biophys. 1981 Jan;206(1):21–28. doi: 10.1016/0003-9861(81)90061-8. [DOI] [PubMed] [Google Scholar]
  12. Oshino N., Imai Y., Sato R. A function of cytochrome b5 in fatty acid desaturation by rat liver microsomes. J Biochem. 1971 Jan;69(1):155–167. doi: 10.1093/oxfordjournals.jbchem.a129444. [DOI] [PubMed] [Google Scholar]
  13. Roughan P. G., Mudd J. B., McManus T. T., Slack C. R. Linoleate and alpha-linolenate synthesis by isolated spinach (Spinacia oleracea) chloroplasts. Biochem J. 1979 Dec 15;184(3):571–574. doi: 10.1042/bj1840571. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Safford R., Nichols B. W. Positional distribution of fatty acids in monogalactosyl diglyceride fractions from leaves and algae. Structural and metabolic studies. Biochim Biophys Acta. 1970 Jun 9;210(1):57–64. doi: 10.1016/0005-2760(70)90061-5. [DOI] [PubMed] [Google Scholar]
  15. Schmidt H., Heinz E. Desaturation of oleoyl groups in envelope membranes from spinach chloroplasts. Proc Natl Acad Sci U S A. 1990 Dec 1;87(23):9477–9480. doi: 10.1073/pnas.87.23.9477. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Schmidt H., Heinz E. Involvement of ferredoxin in desaturation of lipid-bound oleate in chloroplasts. Plant Physiol. 1990 Sep;94(1):214–220. doi: 10.1104/pp.94.1.214. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Smith M. A., Cross A. R., Jones O. T., Griffiths W. T., Stymne S., Stobart K. Electron-transport components of the 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine delta 12-desaturase (delta 12-desaturase) in microsomal preparations from developing safflower (Carthamus tinctorius L.) cotyledons. Biochem J. 1990 Nov 15;272(1):23–29. doi: 10.1042/bj2720023. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Stymne S., Appelqvist L. A. The biosynthesis of linoleate from oleoyl-CoA via oleoyl-phosphatidylcholine in microsomes of developing safflower seeds. Eur J Biochem. 1978 Oct;90(2):223–229. doi: 10.1111/j.1432-1033.1978.tb12594.x. [DOI] [PubMed] [Google Scholar]
  19. Telfer Alison, Cammack R., Evans M. C.W. Hydrogen peroxide as the product of autoxidation of ferredoxin: Reduced either chemically or by illuminated chloroplasts. FEBS Lett. 1970 Sep 18;10(1):21–24. doi: 10.1016/0014-5793(70)80406-9. [DOI] [PubMed] [Google Scholar]

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