Abstract
Low-density lipoprotein (LDL) was separated from the blood serum of the hen by an ultracentrifugal floatation method. Phosphoprotein (LV) was sedimented to the bottom fraction together with other serum proteins of high density. Isolated LDL was soluble in water over a pH range of 9-4, however, rendered insoluble when mixed with LV at an acid pH. Heparin or dextran sulfate also formed insoluble complexes with LDL, and hence the amount of LDL in serum could be determined by measuring the produced turbidity. The titer of serological vitellin reaction of LDL was several times as high as that of LV.
It was assumed that most of yolk lipids might have their origin in LDL of the serum.
