Isolation of esterified fatty acids bound to serum albumin purified from human plasma and characterised by MALDI mass spectrometry

• Published in: Biologicals Vol. 35; no. 1; pp. 43 - 49
• Main Authors: Belgacem, Omar, Stübiger, Gerald, Allmaier, Guenter, Buchacher, Andrea, Pock, Katharina
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2007
• Subjects: Chromatography, Ion Exchange; Electrophoresis, Polyacrylamide Gel; Fatty Acids - chemistry; Fatty Acids - isolation & purification; Human serum albumin; Humans; Lipids; Mass spectrometry; Plasma; Serum Albumin - chemistry; Serum Albumin - isolation & purification; Solutions; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Plasma; Human serum albumin; Lipids; Mass spectrometry
• ISSN: 1045-1056; 1095-8320
• DOI: 10.1016/j.biologicals.2006.01.004

Human serum albumin (HSA) is the most abundant protein in plasma. It is known to transport drugs as well as endogenous ligands, like free fatty acids (FFA). A mass spectrometry based method was applied to analyze the albumin bound lipid ligands. HSA was isolated from a human plasma pool by cold ethanol fractionation and ion exchange chromatography. HSA was defatted using a solvent extraction method to release the copurified lipids bound to the protein. The extracts were then analyzed by matrix-assisted laser desorption ionisation (MALDI) mass spectrometry (MS). Using this method, phospholipids and acylglycerols were detected. The phospholipids were identified to be lyso-phosphatidylcholine (lyso-PC) with distribution of different fatty acids (palmitic, stearic, oleic, and linoleic acids). An abundant species in the HSA lipid extract was found to be a diacylglycerol, composed of two linoleic and/or oleic acid chains. The identified motifs reflect structures that are known to be present in plasma. The binding of lysophospholipids has already been described but it is the first ever-reported evidence of native diacylglycerol ligands bound to HSA. Besides the native ligands from plasma a triacylglycerol was detected that has been added during the albumin preparation steps.