Isolation of pure LpB from human serum

Area of Science:

• Lipid metabolism
• Protein biochemistry
• Cardiovascular research

Background:

• Low-density lipoproteins (LDL) are crucial in lipid transport.
• Isolated LDL often contain non-apoB protein contaminants.
• These contaminants can affect LDL function and research accuracy.

Purpose of the Study:

• To investigate methods for removing non-apoB protein contaminants from LDL.
• To assess the efficacy of triglyceride-rich lipid emulsions (TGRP) in purifying LDL.
• To identify residual contaminants resistant to TGRP treatment.

Main Methods:

• Isolation of LDL via ultracentrifugation.
• Incubation of LDL with artificial triglyceride-rich lipid emulsions (TGRP).
• Analysis of protein content using various biochemical techniques.
• Heparin-Sepharose column chromatography and immunoabsorption.

Main Results:

• TGRP treatment removed apoC and, under certain conditions, apoA proteins from LDL.
• TGRP treatment did not alter LDL lipid composition or flotation behavior.
• ApoE and albumin (up to 0.5% of apoB mass) were resistant to TGRP and heparin-Sepharose.
• Immunoabsorption was necessary for complete removal of apoE and albumin.

Conclusions:

• TGRP is effective in removing certain non-apoB proteins from LDL without altering core properties.
• ApoE and albumin represent recalcitrant contaminants in LDL preparations.
• Immunoabsorption is the definitive method for achieving highly purified LDL, free from apoE and albumin.