Solid-phase extraction of phospholipids from hemoglobin solutions using Empore styrene-divinylbenzene disks

A simple and improved method for extraction of phospholipids from hemoglobin solutions

This study introduced a liquid-liquid extraction method designed for complete recovery of phospholipids from protein-rich samples, such as hemoglobin (Hb) solutions. In order to minimize protein denaturation and maximize lipid extraction from protein-rich samples, isopropanol was used as the major organic extraction solvent. In a wide range of the volume ratio of isopropanol to Hb solution at low temperatures, such extraction system resulted in limited protein precipitation and did not cause heme pigment contamination. The efficiency of phospholipid extraction from Hb solutions was pH-dependent, with the lowest extraction yield around neural pH and the highest extraction yield around pH 5.0. At pH 5.0, salt with concentrations up to 400 mmol/L in the samples did not increase extraction efficiency. Compared to other available methods, this method is simpler, needs significantly less organic solvent and, most importantly, consumed much less Hb, which is very expensive to make for the purpose of production of therapeutic products, hemoglobin-based oxygen carriers (HBOCs). This method is suitable not only for Hb solutions but also for other protein-rich biological samples, such as erythrocytes, plasma and liver.

Stroma-free hemoglobin from bovine blood

Isolation and purification of bovine hemoglobin (HbBv) was carried out after reaction of whole blood with carbon monoxide. Washing/centrifugation steps were used to eliminate leukocytes, platelets, and plasma proteins. Hypotonic media and ultrasound radiation were used to lyse red blood cells. Lyse by ultrasound was shown to lead to solutions at the highest concentrations in HbBv, and the least concentrations in major phospholipids contaminants. Additional purification procedures were performed to remove membrane proteins and phospholipids. In the first case, proteins were denatured by thermal treatment, and filtered. To eliminate phospholipids, liquid chromatography was used with strong anion exchangers. Purity of HbBv was evaluated by normal phase high performance liquid chromatography (HPLC), electrophoresis, and size-exclusion HPLC.

Purification and characterization of human hemoglobin: effect of the hemolysis conditions

Human hemoglobin was isolated and purified by anion exchange chromatography. To isolate hemoglobin, outdated red blood cells (RBC) were transformed into carbonylhemoglobin, by reaction with carbon monoxide, and submitted to washing/centrifugation procedures, to eliminate other plasma proteins. Albumin was quantified in each supernatant, by the bromcresol green method. Hemolysis was performed in three different hypotonic media (water, 0.01 M NaCl and 5 mM Tris/HCl buffer at pH 7.4), at 8 degrees C for 24 h. Sonication for 5 min was also used to lyse RBC. After isolation of hemoglobin, additional purification was carried out by anion exchange chromatography on AG MP-1, Q-SFF and both exchangers. Hemoglobin concentration of hemolysates and of purified solutions were determined by the hemiglobincyanide method. Residual phospholipids were extracted from the four different hemolysates, as well as from the purified hemoglobin solutions, and were analyzed by high performance liquid chromatography. Native and SDS-polyacrylamide gel electrophoresis experiments were performed on purified hemoglobin samples to verify the presence of proteins other than hemoglobin. According to the results, the hemolysis conditions have influence on the purification of hemoglobin.