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. 1973 Sep 1;58(3):689–708. doi: 10.1083/jcb.58.3.689

EFFECTS OF LIPOPROTEIN LIPASE ON THE STRUCTURE OF CHYLOMICRONS

E Joan Blanchette-Mackie 1, Robert O Scow 1
PMCID: PMC2109065  PMID: 4747923

Abstract

Chylomicrons isolated from rat lymph were complexed with lipoprotein lipase of post-heparin plasma (chylomicrons-LPL) in order to study the effects of lipolysis on the structure of chylomicrons. Triglyceride in the chylomicron core was readily hydrolyzed to free fatty acids (FFA) and glycerol when chylomicrons-LPL were incubated at pH 8.3 in medium containing albumin. Although most of the FFA were immediately released to the medium, some were retained within chylomicrons when FFA-binding sites on albumin were not available. These observations suggest that albumin may have a specific role in the transfer of FFA across the chylomicron surface film. Chylomicrons-LPL assumed many different shapes as they were depleted of triglyceride by the lipolytic action of the enzyme, and total removal of core triglyceride resulted in empty sacks of surface film. The surface film was visualized in sections of OsO4-fixed chylomicrons-LPL as a thin electron-opaque line, 25–30 Å wide, in areas where the underlying electron-opaque core had been replaced by zones of decreased electron opacity, and in folds of surface film extending outward from chylomicrons partially depleted of core lipid. The findings demonstrate that chylomicrons consist of a core of liquid triglyceride enveloped by a pliable and durable monolayer surface film, and that lipoprotein lipase reduces the triglyceride core without disrupting the surface film.

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Selected References

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  1. Bergman E. N., Havel R. J., Wolfe B. M., Bohmer T. Quantitative studies of the metabolism of chylomicron triglycerides and cholesterol by liver and extrahepatic tissues of sheep and dogs. J Clin Invest. 1971 Sep;50(9):1831–1839. doi: 10.1172/JCI106674. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bier D. M., Havel R. J. Activation of lipoprotein lipase by lipoprotein fractions of human serum. J Lipid Res. 1970 Nov;11(6):565–570. [PubMed] [Google Scholar]
  3. Blanchette-Mackie E. J., Scow R. O. Sites of lipoprotein lipase activity in adipose tissue perfused with chylomicrons. Electron microscope cytochemical study. J Cell Biol. 1971 Oct;51(1):1–25. doi: 10.1083/jcb.51.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Chernick S., Novak M. Effect of insulin on FFA mobilization and ketosis in fasting pregnant rats. Diabetes. 1970 Aug;19(8):563–570. doi: 10.2337/diab.19.8.563. [DOI] [PubMed] [Google Scholar]
  5. DOLE V. P., MEINERTZ H. Microdetermination of long-chain fatty acids in plasma and tissues. J Biol Chem. 1960 Sep;235:2595–2599. [PubMed] [Google Scholar]
  6. Fraser R. Size and lipid composition of chylomicrons of different Svedberg units of flotation. J Lipid Res. 1970 Jan;11(1):60–65. [PubMed] [Google Scholar]
  7. GORDON R. S., Jr, BOYLE E., BROWN R. K., CHERKES A., ANFINSEN C. B. Role of serum albumin in lipemia clearing reaction. Proc Soc Exp Biol Med. 1953 Oct;84(1):168–170. doi: 10.3181/00379727-84-20579. [DOI] [PubMed] [Google Scholar]
  8. Hamosh M., Clary T. R., Chernick S. S., Scow R. O. Lipoprotein lipase activity of adipose and mammary tissue and plasma triglyceride in pregnant and lactating rats. Biochim Biophys Acta. 1970 Sep 8;210(3):473–482. doi: 10.1016/0005-2760(70)90044-5. [DOI] [PubMed] [Google Scholar]
  9. Havel R. J., Shore V. G., Shore B., Bier D. M. Role of specific glycopeptides of human serum lipoproteins in the activation of lipoprotein lipase. Circ Res. 1970 Oct;27(4):595–600. doi: 10.1161/01.res.27.4.595. [DOI] [PubMed] [Google Scholar]
  10. KAY D., ROBINSON D. S. The structure of chylomicra obtained from the thoracic duct of the rat. Q J Exp Physiol Cogn Med Sci. 1962 Jul;47:258–261. doi: 10.1113/expphysiol.1962.sp001605. [DOI] [PubMed] [Google Scholar]
  11. KORN E. D. The fatty acid and positional specificities of lipoprotein lipase. J Biol Chem. 1961 Jun;236:1638–1642. [PubMed] [Google Scholar]
  12. Lecuyer H., Dervichian D. G. Structure of aqueous mixtures of lecithin and cholesterol. J Mol Biol. 1969 Oct 14;45(1):39–57. doi: 10.1016/0022-2836(69)90208-3. [DOI] [PubMed] [Google Scholar]
  13. Levine Y. K., Wilkins M. H. Structure of oriented lipid bilayers. Nat New Biol. 1971 Mar 17;230(11):69–72. doi: 10.1038/newbio230069a0. [DOI] [PubMed] [Google Scholar]
  14. Mendelson C. R., Scow R. O. Uptake of chylomicron-triglyceride by perfused mammary tissue of lactating rats. Am J Physiol. 1972 Dec;223(6):1418–1423. doi: 10.1152/ajplegacy.1972.223.6.1418. [DOI] [PubMed] [Google Scholar]
  15. RAPPORT M. M., ALONZO N. Photometric determination of fatty acid ester groups in phospholipides. J Biol Chem. 1955 Nov;217(1):193–198. [PubMed] [Google Scholar]
  16. ROBINSON D. S., FRENCH J. E. The role of albumin in the interaction of chyle and plasma in the rat. Q J Exp Physiol Cogn Med Sci. 1953;38(4):233–239. doi: 10.1113/expphysiol.1953.sp001034. [DOI] [PubMed] [Google Scholar]
  17. ROBINSON D. S. THE CLEARING FACTOR LIPASE AND ITS ACTION IN THE TRANSPORT OF FATTY ACIDS BETWEEN THE BLOOD AND TISSUES. Adv Lipid Res. 1963;1:133–182. doi: 10.1016/b978-1-4831-9937-5.50010-7. [DOI] [PubMed] [Google Scholar]
  18. Redgrave T. G. Formation of cholesteryl ester-rich particulate lipid during metabolism of chylomicrons. J Clin Invest. 1970 Mar;49(3):465–471. doi: 10.1172/JCI106255. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Salpeter M. M., Zilversmit D. B. The surface coat of chylomicrons: electron microscopy. J Lipid Res. 1968 Mar;9(2):187–192. [PubMed] [Google Scholar]
  20. Sata T., Havel R. J., Jones A. L. Characterization of subfractions of triglyceride-rich lipoproteins separated by gel chromatography from blood plasma of normolipemic and hyperlipemic humans. J Lipid Res. 1972 Nov;13(6):757–768. [PubMed] [Google Scholar]
  21. Scow R. O., Hamosh M., Blanchette-Mackie E. J., Evans A. J. Uptake of blood triglyceride by various tissues. Lipids. 1972 Aug;7(8):497–505. doi: 10.1007/BF02533015. [DOI] [PubMed] [Google Scholar]
  22. Scow R. O., Stein Y., Stein O. Incorporation of dietary lecithin and lysolecithin into lymph chylomicrons in the rat. J Biol Chem. 1967 Nov 10;242(21):4919–4924. [PubMed] [Google Scholar]
  23. Small D. M. Phase equilibria and structure of dry and hydrated egg lecithin. J Lipid Res. 1967 Nov;8(6):551–557. [PubMed] [Google Scholar]
  24. Spector A. A., John K., Fletcher J. E. Binding of long-chain fatty acids to bovine serum albumin. J Lipid Res. 1969 Jan;10(1):56–67. [PubMed] [Google Scholar]
  25. Stein O., Scow R. O., Stein Y. FFA-3H uptake by perfused adipose tissue: electron microscopic autoradiographic study. Am J Physiol. 1970 Aug;219(2):510–518. doi: 10.1152/ajplegacy.1970.219.2.510. [DOI] [PubMed] [Google Scholar]
  26. VENABLE J. H., COGGESHALL R. A SIMPLIFIED LEAD CITRATE STAIN FOR USE IN ELECTRON MICROSCOPY. J Cell Biol. 1965 May;25:407–408. doi: 10.1083/jcb.25.2.407. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. WHYTE M., KARMEN A., GOODMAN D. S. FATTY ACID ESTERIFICATION AND CHYLOMICRON FORMATION DURING FAT ABSORPTION. 2. PHOSPHOLIPIDS. J Lipid Res. 1963 Jul;4:322–329. [PubMed] [Google Scholar]
  28. Zilversmit D. B. The composition and structure of lymph chylomicrons in dog, rat, and man. J Clin Invest. 1965 Oct;44(10):1610–1622. doi: 10.1172/JCI105267. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Zilversmit D. B. The surface coat of chylomicrons: lipid chemistry. J Lipid Res. 1968 Mar;9(2):180–186. [PubMed] [Google Scholar]

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