Comparative Study of Urea and Betaine Solutions by Dielectric Spectroscopy:  Liquid Structures of a Protein Denaturant and Stabilizer

We performed dielectric spectroscopy measurements on aqueous solutions of glycine betaine (N,N,N-trimethylglycine), which is known to be a strong stabilizer of globular proteins, over a wide concentration range (3−62 wt %) and compared the results with our previously published data for aqueous solut...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2007-10, Vol.111 (40), p.11858-11863
Main Authors: Hayashi, Yoshihito, Katsumoto, Yoichi, Oshige, Ikuya, Omori, Shinji, Yasuda, Akio
Format: Article
Language:English
Subjects:
Betaine - chemistry
Electrochemistry
Protein Denaturation
Solutions
Spectrum Analysis
Urea - chemistry
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Summary:We performed dielectric spectroscopy measurements on aqueous solutions of glycine betaine (N,N,N-trimethylglycine), which is known to be a strong stabilizer of globular proteins, over a wide concentration range (3−62 wt %) and compared the results with our previously published data for aqueous solutions of urea, a representative protein denaturant. The hydration number of betaine (9), calculated on the basis of the reduction in the dielectric relaxation strength of bulk water with addition of betaine, is significantly larger than that of urea (2). Furthermore, the dielectric relaxation time increased with betaine concentration, while that remained nearly constant for the urea−water system over a wide concentration range. This difference between urea and betaine is probably related to their opposite effects on the protein stabilization.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp073238j