title: Population balance modeling of aggregation kinetics of recombinant human interleukin-1 receptor antagonist.
abstract: The kinetics of benzyl alcohol-induced nonnative aggregation of recombinant human interleukin-1 receptor antagonist (rhIL-1ra) were investigated using a population balance model. Steady-state size distributions of rhIL-1ra aggregates formed in a continuous mixed suspension, mixed product removal (MSMPR) reactor were measured and used to extrapolate aggregate nucleation and growth rates parameters. Aggregate growth rate was size-dependent and a linear growth rate model was used to derive a population density function. Addition of 0.9 wt/v% benzyl alcohol increased the nucleation rate by approximately four orders of magnitude. The growth rate for aggregates, however, changed little as a function of benzyl alcohol concentration in the range of 0-0.9%. The addition of sucrose to buffer containing 0.9% benzyl alcohol decreased rhIL1-ra nucleation rate by orders of magnitude and had little impact on growth rate kinetics. The simplicity of the population balance model and the physical relevance of the information obtained from this model render it a useful tool to study protein aggregation kinetics and the effects of excipients on this process.
authors.affiliation: Department of Chemical and Biological Engineering, Center for Pharmaceutical Biotechnology, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Eva Y
authors.initials: EY
authors.lastname: Chi
authors.forename: Brent S
authors.initials: BS
authors.lastname: Kendrick
authors.forename: John F
authors.initials: JF
authors.lastname: Carpenter
authors.forename: Theodore W
authors.initials: TW
authors.lastname: Randolph
mesh_terms: D019905:Benzyl Alcohol / Q000737:chemistry; D005079:Excipients / Q000737:chemistry; D053590:Interleukin 1 Receptor Antagonist Protein; D007700:Kinetics; D008956:Models, Chemical; D011310:Preservatives, Pharmaceutical / Q000737:chemistry; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry*; D012795:Sialoglycoproteins / Q000737:chemistry*
chemical_list: D005079:Excipients; C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D011310:Preservatives, Pharmaceutical; D011994:Recombinant Proteins; D012795:Sialoglycoproteins; D019905:Benzyl Alcohol