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Molten Globule Intermediate of Recombinant Human Growth Hormone: Stabilization with Surfactants
Author(s) -
Bam Narendra B.,
Cleland Jeffrey L.,
Randolph Theodore W.
Publication year - 1996
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp960068b
Subject(s) - molten globule , pulmonary surfactant , chemistry , folding (dsp implementation) , denaturation (fissile materials) , protein folding , recombinant dna , hydrophobic effect , circular dichroism , biophysics , hydrochloride , crystallography , biochemistry , nuclear chemistry , biology , gene , electrical engineering , engineering
Abstract We demonstrate that a surfactant‐stabilized molten globule intermediate exists for recombinant human growth hormone (rhGH), is very hydrophobic, and tends to form aggregates. Characterization of this intermediate included equilibrium denaturation measured by electron paramagnetic resonance (EPR) and CD spectroscopy, assessment of aggregation during refolding, and fluorescence studies of its binding to the hydrophobic probe, 1‐anilinonapthalene‐8‐sulfonate (1,8‐ANS). We have found that at 4.5 M guanidinium hydrochloride (GuHCl), a molten globule intermediate of rhGH is stabilized and results in significant aggregation upon refolding. This intermediate is populated by the addition of the nonionic surfactant, Tween. This surfactant also reduces the extent of aggregation during refolding of rhGH from 4.5 M GuHCl. Overall, our studies reveal that rhGH forms a molten globule‐like intermediate during folding and this intermediate self‐associates. This self‐association is reduced upon formation of a Tween‐rhGH complex. Tween also binds to the native protein. Thus, nonionic surfactants such as Tween may act like molecular chaperones in facilitating protein folding while not altering the native conformation.