Effect of mechanical denaturation on surface free energy of protein powders

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

ABSTRACT
Globular proteins are important both as therapeutic agents and excipients. However, their fragile native conformations can be denatured during pharmaceutical processing, which leads to modification of the surface energy of their powders and hence their performance. Lyophilized powders of hen egg-white lysozyme and β-galactosidase from Aspergillus oryzae were used as models to study the effects of mechanical denaturation on the surface energies of basic and acidic protein powders, respectively. Their mechanical denaturation upon milling was confirmed by the absence of their thermal unfolding transition phases and by the changes in their secondary and tertiary structures. Inverse gas chromatography detected differences between both unprocessed protein powders and the changes induced by their mechanical denaturation. The surfaces of the acidic and basic protein powders were relatively basic, however the surface acidity of β-galactosidase was higher than that of lysozyme. Also, the surface of β-galactosidase powder had a higher dispersive energy compared to lysozyme. The mechanical denaturation decreased the dispersive energy and the basicity of the surfaces of both protein powders. The amino acid composition and molecular conformation of the proteins explained the surface energy data measured by inverse gas chromatography. The biological activity of mechanically denatured protein powders can either be reversible (lysozyme) or irreversible (β-galactosidase) upon hydration. Our surface data can be exploited to understand and predict the performance of protein powders within pharmaceutical dosage forms.
LanguageEnglish
Pages700-706
Number of pages7
JournalColloids and Surfaces B: Biointerfaces
Volume146
Early online date5 Jul 2016
DOIs
StatusPublished - Oct 2016

Fingerprint

Denaturation
biopolymer denaturation
Powders
Free energy
free energy
proteins
Proteins
lysozyme
beta-Galactosidase
Muramidase
Enzymes
Interfacial energy
surface energy
gas chromatography
Gas chromatography
Gas Chromatography
Drug products
Conformations
Membrane Proteins
Aspergillus oryzae

Keywords

  • Keywords: Protein denaturation; β-Galactosidase; Lysozyme; Conformational change; Inverse gas chromatography; Surface free energy.

Cite this

Effect of mechanical denaturation on surface free energy of protein powders. / Blagbrough, Ian.

In: Colloids and Surfaces B: Biointerfaces, Vol. 146, 10.2016, p. 700-706.

Research output: Contribution to journalArticle

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AB - ABSTRACTGlobular proteins are important both as therapeutic agents and excipients. However, their fragile native conformations can be denatured during pharmaceutical processing, which leads to modification of the surface energy of their powders and hence their performance. Lyophilized powders of hen egg-white lysozyme and β-galactosidase from Aspergillus oryzae were used as models to study the effects of mechanical denaturation on the surface energies of basic and acidic protein powders, respectively. Their mechanical denaturation upon milling was confirmed by the absence of their thermal unfolding transition phases and by the changes in their secondary and tertiary structures. Inverse gas chromatography detected differences between both unprocessed protein powders and the changes induced by their mechanical denaturation. The surfaces of the acidic and basic protein powders were relatively basic, however the surface acidity of β-galactosidase was higher than that of lysozyme. Also, the surface of β-galactosidase powder had a higher dispersive energy compared to lysozyme. The mechanical denaturation decreased the dispersive energy and the basicity of the surfaces of both protein powders. The amino acid composition and molecular conformation of the proteins explained the surface energy data measured by inverse gas chromatography. The biological activity of mechanically denatured protein powders can either be reversible (lysozyme) or irreversible (β-galactosidase) upon hydration. Our surface data can be exploited to understand and predict the performance of protein powders within pharmaceutical dosage forms.

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