THE EFFECTS OF EXOGENOUS FREE FATTY-ACIDS ON LIPOPROTEIN MIGRATION INSERUM HIGH-RESOLUTION ELECTROPHORESIS - ADDITION OF FREE FATTY-ACIDS IMPROVES VISUALIZATION OF NORMAL AND ABNORMAL ALPHA(1)-ANTITRYPSIN

Abnormalities in the alpha(1) region are occasionally difficult to int erpret on high-resolution electrophoresis (HRE) gels because alpha(1)- antitrypsin (A(1)AT) can be obscured by elevated levels of lipoprotein . The addition of saturated free fatty acids (SFFAs) to serum samples causes a selective anodal migration of lipoproteins when examined by H RE. This ''clearing'' of the alpha(1) region improves visualization of A(1)AT. In this study, we evaluated 6- to 24-carbon SFFAs for their a bility to cause anodal migration of serum lipoproteins; identified the optimal SFFA and determined its effects on other proteins; and applie d the SFFA to problematic serum samples, including these containing de nse alpha lipoprotein regions. When added to serum samples, a mixture of medium-chain (12-18 carbon) SFFAs caused a dose-dependent anodal mi gration of the alpha and beta lipoproteins and albumin. Lauric acid (C -12:0; 3.2-6.5 mmol/L) caused an optimal effect - maximal anodal migra tion of alpha lipoproteins and clearing of the alpha(1) region, facili tating inspection of that area for A(1)AT variants. At the optimal Cl- 12:0 concentration, the migration and resolution of A(1)AT were minima lly affected, anodal slurring of beta lipoproteins and albumin were sl ight, and there was no effect on interpretation of monoclonal proteins . At higher concentrations, C-12:0 increased anodal migration of beta lipoproteins and decreased the resolution of A(1)AT. C-12:0 at 3.2 mmo l/L in serum samples of heparinized patients showed an exaggerated eff ect similar to higher concentrations of C-12:0 in nonheparinized serum samples. Hyperbilirubinemia did not alter the effect of C-12:0 on ser um proteins. C-12:0 treatment of serum samples displaying dense alpha lipoprotein bands on HRE dramatically improved visualization of A(1)AT . We report the incidental identification of A(1)AT variants in two su ch samples treated with C-12:0. The addition of C-12:0 to serum sample s markedly improves visualization of normal and abnormal A(1)AT in the alpha, region in HRE.