title: Lack of a synergistic effect of arginine-glutamic acid on the physical stability of spray-dried bovine serum albumin.
abstract: Improving the physical stability of spray-dried proteins is essential for enabling pulmonary delivery of biotherapeutics as a noninvasive alternative to injections. Recently, a novel combination of two amino acids - l-arginine (l-Arg) and l-glutamic acid (l-Glu), has been reported to have synergistic protein-stabilizing effects on various protein solutions. Using spray-dried bovine serum albumin (BSA) reconstituted in solution as a model protein, we investigated the synergistic effect of these amino acids on the physical stability of proteins. Five BSA solutions were prepared: (1) BSA with no amino acids (control); (2) with 50 mM l-Arg; (3) with 200 mM l-Arg, (4) with 50 mM l-Glu and (5) with 25:25 mM of Arg:Glu. All solutions were spray-dried and accelerated studies at high temperatures were performed. Following accelerated studies, monomer BSA loss was measured using SE-HPLC. We found that l-Arg significantly improved the physical stability of spray-dried BSA even at low concentrations, however, when combined with l-Glu, was ineffective at reducing monomer BSA loss. Our findings demonstrate the limitations in using Arg-Glu for the stabilization of spray-dried BSA. Furthermore, we found that a low concentration of l-Glu enhanced monomer BSA loss. These findings may have significant implications on the design of future biotherapeutic formulations.
authors.affiliation: a Faculty of Pharmacy , The University of Sydney , Sydney , Australia.
authors.forename: Mouhamad
authors.initials: M
authors.lastname: Reslan
authors.affiliation: a Faculty of Pharmacy , The University of Sydney , Sydney , Australia.
authors.forename: Yusuf K
authors.initials: YK
authors.lastname: Demir
authors.affiliation: b Department of Chemical Engineering , MIT , Cambridge , MA , USA.
authors.forename: Bernhardt L
authors.initials: BL
authors.lastname: Trout
authors.affiliation: a Faculty of Pharmacy , The University of Sydney , Sydney , Australia.
authors.forename: Hak-Kim
authors.initials: HK
authors.lastname: Chan
authors.affiliation: a Faculty of Pharmacy , The University of Sydney , Sydney , Australia.
authors.forename: Veysel
authors.initials: V
authors.lastname: Kayser
mesh_terms: D000818:Animals; D001120:Arginine; D002417:Cattle; D004151:Dipeptides; D018698:Glutamic Acid; D055550:Protein Stability; D012710:Serum Albumin, Bovine / Q000737:chemistry*
chemical_list: D004151:Dipeptides; D012710:Serum Albumin, Bovine; D018698:Glutamic Acid; D001120:Arginine
keywords: Amino acids; excipients; physical stability; protein aggregation; spray-drying