Chemical Characterization of the Serum Very Low Density and High Density Lipoproteins from Bullfrog, Rana catesbeiana

The chemical properties of very low density and high density lipoproteins of adult bullfrog serum were determined. This serum contained extremely low levels of both very low density lipoprotein (10−30 mg/100 ml) and high density lipoprotein (5−10 mg/100 ml).

The constituents of very low density lipoprotein, on a weight percentage basis, were found to be 48.1% triglyceride, 17.3% cholesterol ester, 8.8% cholesterol, 11.6% phospholipid, and 12% protein. These constituents were also present in high density lipoprotein with weight percentage values of 3.7%, 19.3%, 11.9%, 25.2%, and 36.8%, respectively.

The fatty acid compositions of the triglycerides, cholesterol esters, and phosphatidyl-choline were quite similar in the very low density lipoprotein and high density lipoprotein. However, shingomyelin fatty acid composition was appreciably different in the two lipoproteins.

Disc gel electrophoresis in sodium dodecyl sulfate-polyacrylamide gels produced patterns with one major (approximate molecular weight, 7, 000) and several minor bands for the apoprotein of very low density lipoprotein and one major (approximate molecular weight, 28, 000) and several minor bands for that of high density lipoprotein.