Solution formulation and lyophilisation of a recombinant fibronectin fragment

• Published in: European journal of pharmaceutics and biopharmaceutics 2007-09, Vol.67 (2), p.309-319
• Main Authors: Pereira, P., Kelly, S.M., Cooper, A., Mardon, H.J., Gellert, P.R., van der Walle, C.F.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Calorimetry; Calorimetry, Differential Scanning; Cell Adhesion; Circular Dichroism; Cricetinae; Fibronectin; Fibronectins - chemistry; Formulation; General pharmacology; Hot Temperature; Hydrogen-Ion Concentration; Medical sciences; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Polyethylene Glycols - chemistry; Recombinant Fusion Proteins - chemistry; Spectrometry, Fluorescence; Structure-Activity Relationship; Sucrose - chemistry; Thermal stability; Tissue Engineering
• ISSN: 0939-6411; 1873-3441
• DOI: 10.1016/j.ejpb.2007.03.009

The 9th–10th type III fibronectin domain pair shows promise in tissue engineering and tumour vasculature targeting. Calorimetry and structure–function analysis were used to investigate the effects of solution formulation and lyophilisation of a mutant ( 9–10FNIII-P). A single endothermic transition for 9–10FNIII-P in solution was observed at pH < 8, irrespective of addition of sucrose or PEG. The temperature at the maximum heat capacity ( T m) and enthalpy (Δ H) of the transition increased for increasing sucrose concentrations but decreased for increasing PEG concentrations. The transition was fitted to a single two-state unfolding mechanism (in contrast to unfolding in guanidine·HCl) and was partially reversible only at pH 4, with increasing concentrations of sucrose causing a marked fall in Δ H between scans. Circular dichroism spectra for the thermal unfolding of 9–10FNIII-P at pH 4 showed loss of native β-sheet structure and loss of aromatic contributions to the peak centred around 226 nm yielding an intermediate conformation, which in the presence of sucrose was more disordered. Despite a glass transition ( T g ′ ) for 9–10FNIII-P (aq) of −70 °C, primary drying at −30 °C did not perturb its conformation upon reconstitution or its biological activity following lyophilisation; the addition of sucrose or PEG had no influence on structure or activity. The main consideration in the formulation of 9–10FNIII-P was therefore pH.