The Characterization and Occurrence of an S 20 Serum Lipoprotein

Quantitative analysis of serum lipoproteins by micro-scale thin-layer chromatography

A method has been devised for the complete chemical analysis of serum lipoproteins, in which the constituents are separated by thin-layer chromatography and then measured by means of a flame ionisation detector. Since the response of the detector differs for each constituent, it is necessary to use a previously prepared calibration curve for each one. A complete analysis can be obtained from a single run on about 20 microgram of lipoprotein. However, from 5--10 chromatograms are needed for an adequate degree of precision. The method, which could be adapted to the measurement of tissue lipids, takes less than 2 h to complete. This speed and simplicity seem to give the method considerable potential for the investigation of patients with disorders of lipid transport.

Studies on a beta-migrating high density lipoprotein

An unusual serum lipoprotein (Lp) profile was detected in a Japanese family. A double beta-Lp was observed when serum was subjected to polyacrylamide gel electrophoresis. The slower migrating beta-Lp was identified as a subfraction of high density lipoprotein (HDL). It was present in the d 1.063--1.21 fraction, migrated to the position designated as the midband L.1 (sinking pre-beta-lipoprotein) by Mead, M.G. and Dangerfield, W.G. (1974) (Clin. Chim. Acta 51, 173--182) [1], and reacted against human anti-beta-Lp antiserum. This lipoprotein contained greater amounts of triglyceride than the usual beta-lipoprotein and could not be clearly detected by paper electrophoresis. Individuals exhibiting this high density midband lipoprotein appeared to be heterozygous for an autosomal dominant gene. Although other reports have indicated the possibility of a positive association between the occurrence of serum lipoproteins with unusual eletrophoretic mobility and premature ischemic heart disease, no such correlation was demonstrable in these subjects.

Structural and compositional changes attending the ultracentrifugation of very low density lipoproteins

The effects of repetitive ultracentrifugation on the physical and chemical properties of very low density lipoproteins (VLDL) were investigated. VLDL recentrifuged one to seven times were characterized by chemical analyses, analytical ultracentrifugation and electron microscopy. The VLDL content of triglyceride was increased and the proportion of phospholipid decreased by ultracentrifugation. Recentrifugation of VLDL decreased the number of Sf-o 20-100 particles and generated particles of Sf-o greater than 400. The bulk of the material removed from VLDL by ultracentrifugation was lipoprotein having pre-beta mobility on paper electrophoresis, flotation rates of Sf-o 10-100 and a particle size of 300-400 A-O. Two ultracentrifugations separated an average of 14% of the starting VLDL protein. Characterization of the apoproteins in this material by polyacrylamide gel electrophoresis, gel chromatography, immunoprecipitation and amino acid analysis demonstrated a relatively high proportion of beta-apoprotein and relatively little C-apoproteins.