Proline inhibits aggregation during protein refolding.
The in vitro refolding of hen egg-white lysozyme is studied in the presence of various osmolytes. Proline is found to prevent aggregation during protein refolding. However, other osmolytes used in this study fail to exhibit a similar property. Experimental evidence suggests that proline inhibits protein aggregation by binding to folding intermediate(s) and trapping the folding intermediate(s) into enzymatically inactive, "aggregation-insensitive" state(s). However, elimination of proline from the refolded protein mixture results in significant recovery of the bacteriolytic activity. At higher concentrations (>1.5 M), proline is shown to form loose, higher-order molecular aggregate(s). The supramolecular assembly of proline is found to possess an amphipathic character. Formation of higher-order aggregates is believed to be crucial for proline to function as a protein folding aid. In addition to its role in osmoregulation under water stress conditions, the results of this study hint at the possibility of proline behaving as a protein folding chaperone.
Samuel
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D
Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
Kumar
T K
TK
Ganesh
G
G
Jayaraman
G
G
Yang
P W
PW
Chang
M M
MM
Trivedi
V D
VD
Wang
S L
SL
Hwang
K C
KC
Chang
D K
DK
Yu
C
C
D000818:Animals; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D009113:Muramidase / Q000737:chemistry / Q000302:isolation & purification; D010084:Oxidation-Reduction; D011392:Proline / Q000494:pharmacology*; D011489:Protein Denaturation; D017510:Protein Folding; D013050:Spectrometry, Fluorescence
D046911:Macromolecular Substances; D011392:Proline; D009113:Muramidase