Isolation and properties of a lipoprotein from the haemolymph of the locust, Locusta migratoria

A yellow lipoprotein was isolated from the haemolymph of the migratory locust by ethanol precipitation and sucrose gradient centrifugation. The lipoprotein contained 30% lipids, 80% of which were diglycerides and phospholipids. The yellow colour was due to the presence of carotenoids. A mol w of 340,000 ± 50,000 was calculated from sedimentation equilibrium measurements. By electrophoresis in sodium dodecyl sulphate-gels the lipoproteins separated into several polypeptides. The capacity of the purified lipoprotein to promote diglyceride release was lower than that of the haemolymph. Full activity was restored by the addition of a protein from the haemolymph, which by itself showed little activity.