Abstract
Chylomicrons were separated by low and high speed ultracentrifugation from lipemic sera of human subjects in the absorptive phase. The final chylomicron preparation was free from other serum components and contained a small constant amount of protein, approximately 2 per cent of the chylomicron fraction. Electrophoresis, immunochemical analysis, and absorption experiments identified the protein component as derived from a mixture of beta and alpha1 serum lipoproteins. Large aliquots of an emulsion of serum freed of chylomicrons and coconut oil were incubated at 37°C. for 2 hours and ultracentrifuged as in the preparation of chylomicrons. The fat particles now showed the presence of minute amounts of beta and alpha1 serum lipoproteins in almost the same proportion as found in chylomicrons. "Finger prints" of delipidized samples of chylomicrons and particles from serum-coconut oil emulsion gave similar, although not identical patterns. The data on "clearing factor" activity corroborated the finding that serum alpha1 lipoproteins are contained in chylomicrons and particles from serum-coconut oil emulsion. These two lipide particles, partially delipidized, were both able to activate a "clearing factor" system in vitro, a property exhibited only by intact or partially delipidized alpha1 serum lipoproteins. Clearing activity was satisfactorily determined by using an emulsion of coconut oil mixed in agar as a substrate to give an opaque gel, in which the diffusing enzyme showed its activity by areas of clearing. The results obtained by this technique were in agreement with those based on fall in optical density and non-esterified fatty acid production. Chemical analysis of serum chylomicrons showed a concentration of cholesterol and phospholipides higher than could be accounted for by the attached beta and alpha1 serum lipoproteins. On the basis of these results the assumption is made that in the blood stream small amounts of serum lipoproteins, by a process of adsorption, form a complex with the absorbed triglycerides, cholesterol, and phospholipides, to produce chylomicrons.
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Selected References
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- ABEL L. L., LEVY B. B., BRODIE B. B., KENDALL F. E. A simplified method for the estimation of total cholesterol in serum and demonstration of its specificity. J Biol Chem. 1952 Mar;195(1):357–366. [PubMed] [Google Scholar]
- AVIGAN J., REDFIELD R., STEINBERG D. N-terminal residues of serum lipoproteins. Biochim Biophys Acta. 1956 Jun;20(3):557–558. doi: 10.1016/0006-3002(56)90354-7. [DOI] [PubMed] [Google Scholar]
- BLOMSTRAND R., THORN N. A., AHRENS E. H., Jr The absorption of fats, studied in a patient with chyluria. I. Clinical investigation. Am J Med. 1958 Jun;24(6):958–966. doi: 10.1016/0002-9343(58)90348-6. [DOI] [PubMed] [Google Scholar]
- BRAGDON J. H. On the composition of chyle chylomicrons. J Lab Clin Med. 1958 Oct;52(4):564–570. [PubMed] [Google Scholar]
- BURSTEIN M., SAMAILLE J. Sur une nouvelle méthode de préparation d'un immunsérum anti-beta-lipoprotéines spécifique. Rev Fr Etud Clin Biol. 1958 Jun;3(6):624–626. [PubMed] [Google Scholar]
- FREDRICKSON D. S., HAVEL R. J. The metabolism of chylomicra. I. The removal of palmitic acid-1-C14 labeled chylomicra from dog plasma. J Clin Invest. 1956 Sep;35(9):1025–1032. doi: 10.1172/JCI103348. [DOI] [PMC free article] [PubMed] [Google Scholar]
- GILLMAN T., NAIDOO S. S. In vitro effects of heparin and calcium ions on lipaemic serum. Nature. 1957 May 4;179(4566):904–905. doi: 10.1038/179904a0. [DOI] [PubMed] [Google Scholar]
- INGRAM V. M. Abnormal human haemoglobins. I. The comparison of normal human and sickle-cell haemoglobins by fingerprinting. Biochim Biophys Acta. 1958 Jun;28(3):539–545. doi: 10.1016/0006-3002(58)90516-x. [DOI] [PubMed] [Google Scholar]
- KORN E. D. Clearing factor, a heparin-activated lipoprotein lipase. II. Substrate specificity and activation of coconut oil. J Biol Chem. 1955 Jul;215(1):15–26. [PubMed] [Google Scholar]
- LAURELL C. B. Composition of chylomicrons isolated from rat's lymph. Acta Physiol Scand. 1954;30(2-3):289–294. doi: 10.1111/j.1748-1716.1954.tb01097.x. [DOI] [PubMed] [Google Scholar]
- LAURELL C. B. Preliminary data on the composition and certain properties of human chylomicrons. Scand J Clin Lab Invest. 1954;6(1):22–24. [PubMed] [Google Scholar]
- LEVINE L., KAUFFMAN D. L., BROWN R. K. The antigenic similarity of human low density lipoproteins. J Exp Med. 1955 Aug 1;102(2):105–118. doi: 10.1084/jem.102.2.105. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LINDGREN F. T., ELLIOTT H. A., GOFMAN J. W. The ultracentrifugal characterization and isolation of human blood lipids and lipoproteins, with applications to the study of atherosclerosis. J Phys Colloid Chem. 1951 Jan;55(1):80–93. doi: 10.1021/j150484a010. [DOI] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- MIDDLETON E., Jr Immunochemical relationship of human plasma beta-lipoprotein and chylomicrons. Am J Physiol. 1956 May;185(2):309–312. doi: 10.1152/ajplegacy.1956.185.2.309. [DOI] [PubMed] [Google Scholar]
- NECHELES H. The phenomenon of chylomicrons in fat absorption and arteriosclerosis. Am J Dig Dis. 1951 Aug;18(8):229–231. doi: 10.1007/BF02891984. [DOI] [PubMed] [Google Scholar]
- ROBINSON D. S. The chemical composition of chylomicra in the rat. Q J Exp Physiol Cogn Med Sci. 1955 Apr;40(2):112–126. doi: 10.1113/expphysiol.1955.sp001103. [DOI] [PubMed] [Google Scholar]
- RODBELL M. N-terminal amino acid and lipid composition of lipoproteins from chyle and plasma. Science. 1958 Mar 28;127(3300):701–702. doi: 10.1126/science.127.3300.701. [DOI] [PubMed] [Google Scholar]
- RODBELL M. N-terminal amino acid and lipid composition of lipoproteins from chyle and plasma. Science. 1958 Mar 28;127(3300):701–702. doi: 10.1126/science.127.3300.701. [DOI] [PubMed] [Google Scholar]
- SCANU A., LEWIS L. A., BUMPUS F. M. Separation and characterization of the protein moiety of human alpha1-lipoprotein. Arch Biochem Biophys. 1958 Apr;74(2):390–397. doi: 10.1016/0003-9861(58)90009-2. [DOI] [PubMed] [Google Scholar]
- SCANU A., LEWIS L. A., PAGE I. H. Studies on the antigenicity of beta- and alpha-lipoproteins of human serum. J Exp Med. 1958 Aug 1;108(2):185–196. doi: 10.1084/jem.108.2.185. [DOI] [PMC free article] [PubMed] [Google Scholar]
- SCHOTZ M. C., SCANU A., PAGE I. H. Effect of triton on lipoprotein lipase of rat plasma. Am J Physiol. 1957 Feb;188(2):399–402. doi: 10.1152/ajplegacy.1957.188.2.399. [DOI] [PubMed] [Google Scholar]
- SHORE B. C-and N-terminal amino acids of human serum lipoproteins. Arch Biochem Biophys. 1957 Sep;71(1):1–10. doi: 10.1016/0003-9861(57)90002-4. [DOI] [PubMed] [Google Scholar]
- SWANK R. L., FELLMAN J. H. Plasma proteins and fat transport in dogs. Am J Physiol. 1958 Feb;192(2):318–324. doi: 10.1152/ajplegacy.1958.192.2.318. [DOI] [PubMed] [Google Scholar]
- SWANK R. L., WILMOT V. Chylomicra; their composition and their fate after intravenous injection of small amounts of heparin. Am J Physiol. 1951 Nov;167(2):403–412. doi: 10.1152/ajplegacy.1951.167.2.403. [DOI] [PubMed] [Google Scholar]
- VAN HANDEL E., ZILVERSMIT D. B. Micromethod for the direct determination of serum triglycerides. J Lab Clin Med. 1957 Jul;50(1):152–157. [PubMed] [Google Scholar]
