title: Unfolding properties of recombinant human serum albumin products are due to bioprocessing steps.
abstract: We have used differential scanning calorimetry (DSC) to determine the unfolding properties of commercial products of human serum albumin (HSA) prepared from pooled human blood, transgenic yeast, and transgenic rice. The initial melting temperatures (Tm1 ) for the unfolding transitions of the HSA products varied from 62°C to 75°C. We characterized the samples for purity, fatty acid content, and molecular weight. The effects of adding fatty acids, heat pasteurization, and a low pH defatting technique on the transition temperatures were measured. Defatted HSA has a structure with the lowest stability (Tm of ∼62°C). When fatty acids are bound to HSA, the structure is stabilized (Tm of ∼64-72°C), and prolonged heating (pasteurization at 60°C) results in a heat-stabilized structural form containing fatty acids (Tm of ∼75-80°C). This process was shown to be reversible by a low pH defatting step. This study shows that the fatty acid composition and bioprocessing history of the HSA commercial products results in the large differences in the thermal stability.
authors.affiliation: National Inst. of Standards and Technology, Biosystems and Biomaterials Div., Gaithersburg, MD, 20899.
authors.forename: Brian E
authors.initials: BE
authors.lastname: Lang
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Cole
mesh_terms: D001709:Biotechnology; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D005227:Fatty Acids / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D012275:Oryza / Q000235:genetics / Q000378:metabolism; D058767:Protein Unfolding; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012709:Serum Albumin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D013816:Thermodynamics; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D011994:Recombinant Proteins; D012709:Serum Albumin
keywords: and thermodynamics; biopharmaceutical; differential scanning calorimetry (DSC); human serum albumin; recombinant proteins; thermal unfolding