Stability of crystallised and spray-dried lysozyme

Moisture and temperature promote protein degradation. The stabilities of commercial, crystallised and spray-dried lysozyme, a model protein, were assessed under these stresses to explore whether a crystalline protein had better storage stability than a conventionally produced one. Samples were maint...

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Bibliographic Details
Published in:International journal of pharmaceutics 2004-07, Vol.278 (2), p.209-219
Main Authors: Elkordy, Amal A, Forbes, Robert T, Barry, Brian W
Format: Article
Language:English
Subjects:
Biological and medical sciences
Calorimetry
Crystallisation
Crystallization
Enzyme Stability
Fourier Analysis
General pharmacology
Lysozyme
Medical sciences
Muramidase - chemistry
Pharmaceutical technology. Pharmaceutical industry
Pharmacology. Drug treatments
Raman
Spectrum Analysis, Raman
Spray-dried
Stability
Technology, Pharmaceutical
Temperature
Thermogravimetry
Water - chemistry
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Summary:Moisture and temperature promote protein degradation. The stabilities of commercial, crystallised and spray-dried lysozyme, a model protein, were assessed under these stresses to explore whether a crystalline protein had better storage stability than a conventionally produced one. Samples were maintained at different relative humidities (RH) and temperatures for 20 weeks and stabilities estimated in solid and aqueous states. Differential scanning calorimetry (DSC) and thermogravimetry (TGA) characterised solid samples. Fourier transform Raman (FT-Raman) spectroscopy analysed solid material and aqueous solutions. High sensitivity differential scanning calorimetry (HSDSC) and enzymatic assays were used to monitor solutions. DSC and HSDSC data revealed that crystals maintained thermal stability at high RH; spray drying appreciably changed melting characteristics. These results correlated with enzymatic assays that demonstrated good activity retention for crystals but less so for spray-dried material (e.g. 95 and 87% relative to fresh samples after 20 weeks at 40 °C/75% RH). FT-Raman analysis showed that crystallised lysozyme better-maintained protein conformational integrity compared to spray-dried samples in accelerated stability studies. Based on TGA data, spray-dried protein absorbed water on storage under humid conditions, which induced instability. Thus, crystallisation enhanced storage stability of lysozyme with negligible loss of activity.
ISSN:0378-5173
1873-3476
DOI:10.1016/j.ijpharm.2004.02.027