Stabilization of Human Albumin by Caprylate and Acetyltryptophanate

Abstract

The thermal stabilization of human albumin by caprylate (CA) and acetyltryptophanate (AT) was studied by monitoring the formation of albumin polymer (defined as species larger than dimer) on the basis of its molecular size as well as its characteristic migration as α-globulin. Heating 5% protein solutions of purified albumin monomer, Cohn fraction V, and fraction IV-4 + V at 60°C in 0.1 M sodium phosphate or 145 mM sodium chloride, pH 7.0, established the following order of stabilizer effectiveness: 4 mM CA + 4mM AT ≈ 4 mM CA>8 mM AT≥2mM CA>4 mM AT. However, albumin was more thermally stable in the chloride medium. Raising the CA concentration above 4 mM provided little additional stabilization. The D- and L-enantiomers of AT were equally effective, but 16 mM AT was needed to equal the effect of 4 mM CA. L-Tryptophanate exerted only slight stabilization, even at 32 mM\ D-tryptophanate was even less effective. The albumin polymer level increased progressively with time at 60 °C in 2 mM CA or 4 mM AT, whereas in 4 mM CA it reached a plateau in 4-6 h. Acetone drying of albumin-rich fractions was shown to remove nearly all endogenous fatty acid, rendering the protein thermally labile unless sufficient exogenous stabilizer(s) was added. Even in the presence of 145 mM sodium chloride and 4 mM CA + 4 mM AT or 4 mM CA, the stabilizing effect of endogenous fatty acid was still detectable.

25% Human Serum Albumin Improves Hemodynamics and Prevents the Need for Nearly All Pre-Hospital Resuscitation in a Rat (Rattus Norvegicus) Model of Trauma and Hemorrhage

“…In addition to coming from the ischemic gut, NEFA may be released by burn injuries, bone fractures, or be administered with resuscitation (8–10). Pharmaceutical albumin is stabilized for heat sterilization by adding approximately 10 times the physiologic concentration of NEFA (11,12). In vitro , we showed that at these concentrations and at concentrations measured in shock, NEFA in the presence of blood cells detaches from albumin, disrupts cell membranes, and induces hemolysis (11).…”

Increase of Octanoate Concentrations During Extracorporeal Albumin Dialysis Treatments

“…Therapeutic use of human serum albumin (HSA) is recommended in the treatment of complications of liver cirrhosis, such as hepatorenal syndrome, or after paracentesis (1)(2)(3). Pharmaceutical-grade albumin preparations contain a high amount of medium fatty acid octanoate and tryptophan as stabilizers, which are a prerequisite for virus inactivation and the avoidance of macromolecule formation during the preparation process (4)(5)(6). Content of those stabilizers in pharmaceutical-grade HSA preparations are several times higher than albumin concentration, up to a molar ratio of 5.4 mol/mol (7,8).…”