Aggregation of recombinant human interferon gamma: kinetics and structural transitions.
Protein aggregation is a complex phenomenon that can occur in vitro and in vivo, usually resulting in the loss of the protein's biological activity. While many aggregation studies focus on a mechanism due to a specific stress, this study focuses on the general nature of aggregation. Recombinant human interferon-gamma (rhIFN-gamma) provides an ideal model for studying protein aggregation, as it has a tendency to aggregate under mild denaturing stresses (low denaturant concentration, temperature below the Tm, and below pH 5). All of the aggregates induced by these stresses have a similar structure (high in intermolecular beta-sheet content and a large loss of alpha-helix) as determined by infrared and circular dichroism spectroscopy. Thermally induced and denaturant-induced aggregation processes follow first-order kinetics under the conditions of this study. Spectroscopic and kinetic data suggest that rhIFN-gamma aggregates through an intermediate form possessing a large amount of residual secondary structure. In contrast to the aggregates formed under denaturing stresses, the salted-out protein has a remarkably nativelike secondary structure.
Kendrick
B S
BS
Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, Campus Box C238, Denver, Colorado 80262, USA.
Cleland
J L
JL
Lam
X
X
Nguyen
T
T
Randolph
T W
TW
Manning
M C
MC
Carpenter
J F
JF
D006801:Humans; D007371:Interferon-gamma / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D011994:Recombinant Proteins; D013057:Spectrum Analysis
D011994:Recombinant Proteins; D007371:Interferon-gamma