Size distributions of chylomicrons from human lymph from dynamic light scattering measurements

Chylomicrons, the vehicles for the transport of exogeneous triglycerides an d cholesterol in the lymph and the blood, were characterized by their size from dynamic light scattering measurements. To achieve an appropriate resol ution, correlation data were collected over several hours. Analysis was per formed with an extended version of the regularization method CONTIN, and sp ecial attention was given to errors in the experimental baseline and to ran domness of the residuals. The solutions selected by means of Fisher's F-tes t by CONTIN agreed with those obtained with the stability plot of Schnableg ger and Glatter, when in the case of data of lower statistical accuracy the . solution was taken from the lower part of the confidence interval of the F-test. The intensity-weighted size distributions indicated two classes of particle, their mean diameters being 100-140 nm and 330-350 nm. The ability to resolve two peaks of such a size ratio is demonstrated. The numbers of particles associated with the two peaks were estimated by means of the scat tering properties of the particles, which showed that the overwhelming majo rity were small ones. This estimation also suggested that the mean size of the first peak of the number distribution is significantly smaller than the typical size of chylomicrons. This was consistent with the finding that th e sample contained not only apolipoprotein B-48 but also a similar amount o f apolipoprotein B-100, which is associated with lipoproteins of smaller si ze. The larger particles of the second peak are probably dietary triglyceri de-rich chylomicrons.