Skip to main content
PMC home page
Biochemical Journal logoLink to Biochemical Journal
. 1990 Nov 15;272(1):23–29. doi: 10.1042/bj2720023

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.

M A Smith 1, A R Cross 1, O T Jones 1, W T Griffiths 1, S Stymne 1, K Stobart 1
PMCID: PMC1149651  PMID: 2264826

Abstract

The major cytochrome in microsomal membrane preparations from developing seeds of safflower (Carthamus tinctorius, var High Linoleate), has a reduced-minus-oxidized difference spectrum characteristic of a b-type cytochrome, and was identified from its midpoint-potential (E'7.2) value as cytochrome b5. Cytochromes P-450 and P-420 were also present. The cytochrome b5 content of microsomal preparations from a number of oilseed species was found to be in the order of 200-300 pmol/mg of protein. The cytochrome b5 was reduced in the membrane preparations by NADH, demonstrating the presence of an NADH: cytochrome b5 reductase; NADPH was a less effective donor. Microsomal membranes catalysed the NAD(P)H-dependent conversion of radioactive oleate into linoleate, indicating acyl-CoA: lysophosphatidylcholine acyltransferase and 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine delta 12-desaturase (delta 12-desaturase) activity. Desaturation of oleate to linoleate was unaffected by CO, but inhibited by CN-. The addition of oleoyl-CoA to the NADH-reduced membranes resulted in the CN(-)-sensitive partial re-oxidation of cytochrome b5, indicating that electrons from NADH were transferred to the site of desaturation via this cytochrome. The delta 12-desaturase in safflower, therefore, is CN(-)-sensitive and appears to require cytochrome b5 and NADH: cytochrome b5 reductase for activity.

Full text

PDF
23

Selected References

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

  1. Asard H., Venken M., Caubergs R., Reijnders W., Oltmann F. L., De Greef J. A. b-Type Cytochromes in Higher Plant Plasma Membranes. Plant Physiol. 1989 Jul;90(3):1077–1083. doi: 10.1104/pp.90.3.1077. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. BLIGH E. G., DYER W. J. A rapid method of total lipid extraction and purification. Can J Biochem Physiol. 1959 Aug;37(8):911–917. doi: 10.1139/o59-099. [DOI] [PubMed] [Google Scholar]
  3. Bonnerot C., Galle A. M., Jolliot A., Kader J. C. Purification and properties of plant cytochrome b5. Biochem J. 1985 Feb 15;226(1):331–334. doi: 10.1042/bj2260331. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Dutton P. L. Redox potentiometry: determination of midpoint potentials of oxidation-reduction components of biological electron-transfer systems. Methods Enzymol. 1978;54:411–435. doi: 10.1016/s0076-6879(78)54026-3. [DOI] [PubMed] [Google Scholar]
  5. Enoch H. G., Catalá A., Strittmatter P. Mechanism of rat liver microsomal stearyl-CoA desaturase. Studies of the substrate specificity, enzyme-substrate interactions, and the function of lipid. J Biol Chem. 1976 Aug 25;251(16):5095–5103. [PubMed] [Google Scholar]
  6. Estabrook R. W., Werringloer J. The measurement of difference spectra: application to the cytochromes of microsomes. Methods Enzymol. 1978;52:212–220. doi: 10.1016/s0076-6879(78)52024-7. [DOI] [PubMed] [Google Scholar]
  7. Gennity J. M., Stumpf P. K. Studies of the delta 12 desaturase of Carthamus tinctorius L. Arch Biochem Biophys. 1985 Jun;239(2):444–454. doi: 10.1016/0003-9861(85)90710-6. [DOI] [PubMed] [Google Scholar]
  8. Harris R. V., James A. T. Linoleic and alpha-linolenic acid biosynthesis in plant leaves and green alga. Biochim Biophys Acta. 1965 Dec 2;106(3):456–464. doi: 10.1016/0005-2760(65)90062-7. [DOI] [PubMed] [Google Scholar]
  9. Hendry G. A., Houghton J. D., Jones O. T. The cytochromes in microsomal fractions of germinating mung beans. Biochem J. 1981 Mar 15;194(3):743–751. doi: 10.1042/bj1940743. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Jaworski J. G., Stumpf P. K. Fat metabolism in higher plants. Properties of a soluble stearyl-acyl carrier protein desaturase from maturing Carthamus tinctorius. Arch Biochem Biophys. 1974 May;162(1):158–165. doi: 10.1016/0003-9861(74)90114-3. [DOI] [PubMed] [Google Scholar]
  11. Jollie D. R., Sligar S. G., Schuler M. Purification and Characterization of Microsomal Cytochrome b(5) and NADH Cytochrome b(5) Reductase from Pisum sativum. Plant Physiol. 1987 Oct;85(2):457–462. doi: 10.1104/pp.85.2.457. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. KATES M. SIMPLIFIED PROCEDURES FOR HYDROLYSIS OR METHANOLYSIS OF LIPIDS. J Lipid Res. 1964 Jan;5:132–135. [PubMed] [Google Scholar]
  13. McKeon T. A., Stumpf P. K. Purification and characterization of the stearoyl-acyl carrier protein desaturase and the acyl-acyl carrier protein thioesterase from maturing seeds of safflower. J Biol Chem. 1982 Oct 25;257(20):12141–12147. [PubMed] [Google Scholar]
  14. Mihara K., Sato R. Detergent-solubilized NADH-cytochrome b5 reductase. Methods Enzymol. 1978;52:102–108. doi: 10.1016/s0076-6879(78)52011-9. [DOI] [PubMed] [Google Scholar]
  15. 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]
  16. Nagai J., Bloch K. Enzymatic desaturation of stearyl acyl carrier protein. J Biol Chem. 1968 Sep 10;243(17):4626–4633. [PubMed] [Google Scholar]
  17. OMURA T., SATO R. THE CARBON MONOXIDE-BINDING PIGMENT OF LIVER MICROSOMES. I. EVIDENCE FOR ITS HEMOPROTEIN NATURE. J Biol Chem. 1964 Jul;239:2370–2378. [PubMed] [Google Scholar]
  18. 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]
  19. Oshino N., Imai Y., Sato R. Electron-transfer mechanism associated with fatty acid desaturation catalyzed by liver microsomes. Biochim Biophys Acta. 1966 Oct 17;128(1):13–27. doi: 10.1016/0926-6593(66)90137-8. [DOI] [PubMed] [Google Scholar]
  20. Rich P. R., Bendall D. S. Cytochrome components of plant microsomes. Eur J Biochem. 1975 Jul 1;55(2):333–341. doi: 10.1111/j.1432-1033.1975.tb02167.x. [DOI] [PubMed] [Google Scholar]
  21. Roughan P. G. Turnover of the glycerolipids of pumpkin leaves. The importence of phosphatidylcholine. Biochem J. 1970 Mar;117(1):1–8. doi: 10.1042/bj1170001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Slack C. R., Roughan P. G., Balasingham N. Labelling of glycerolipids in the cotyledons of developing oilseeds by [1-14C] acetate and [2-3H] glycerol. Biochem J. 1978 Feb 15;170(2):421–433. doi: 10.1042/bj1700421. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Snow G. A. Mycobactins: iron-chelating growth factors from mycobacteria. Bacteriol Rev. 1970 Jun;34(2):99–125. doi: 10.1128/br.34.2.99-125.1970. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Strittmatter P., Spatz L., Corcoran D., Rogers M. J., Setlow B., Redline R. Purification and properties of rat liver microsomal stearyl coenzyme A desaturase. Proc Natl Acad Sci U S A. 1974 Nov;71(11):4565–4569. doi: 10.1073/pnas.71.11.4565. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. 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]
  26. Stymne S., Stobart A. K. Evidence for the reversibility of the acyl-CoA:lysophosphatidylcholine acyltransferase in microsomal preparations from developing safflower (Carthamus tinctorius L.) cotyledons and rat liver. Biochem J. 1984 Oct 15;223(2):305–314. doi: 10.1042/bj2230305. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Stymne S., Stobart A. K., Glad G. The role of the acyl-CoA pool in the synthesis of polyunsaturated 18-carbon fatty acids and triacylglycerol production in the microsomes of developing safflower seeds. Biochim Biophys Acta. 1983 Jul 12;752(2):198–208. doi: 10.1016/0005-2760(83)90113-3. [DOI] [PubMed] [Google Scholar]
  28. Stymne S., Stobart A. K. The biosynthesis of triacylglycerols in microsomal preparations of developing cotyledons of sunflower (Helianthus annuus L.). Biochem J. 1984 Jun 1;220(2):481–488. doi: 10.1042/bj2200481. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Sánchez M., Nicholls D. G., Brindley D. N. [The relationship between palmitoyl-coenzyme A synthetase activity and esterification of sn-glycerol 3-phosphate in rat liver mitochondria]. Biochem J. 1973 Apr;132(4):697–706. doi: 10.1042/bj1320697. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Vijay I. K., Stumpf P. K. Fat metabolism in higher plants. 48. Properties of oleyl coenzyme A desaturase of Carthamus tinctorius. J Biol Chem. 1972 Jan 25;247(2):360–366. [PubMed] [Google Scholar]

Articles from Biochemical Journal are provided here courtesy of The Biochemical Society

RESOURCES