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Main Title: The influence of poly(ethylene glycol) on the micelle formation of alkyl maltosides used in membrane protein crystallization
Author(s): Müh, Frank
DiFiore, Dörte
Zouni, Athina
Type: Article
Language Code: en
Abstract: With the aim of better understanding the phase behavior of alkyl maltosides (n-alkyl-beta-D-maltosides, C(n)G(2)) under the conditions of membrane protein crystallization, we studied the influence of poly(ethylene glycol) (PEG) 2000, a commonly used precipitating agent, on the critical micelle concentration (CMC) of the alkyl maltosides by systematic variation of the number n of carbon atoms in the alkyl chain (n = 10, 11, and 12) and the concentration of PEG2000 (chi) in a buffer suitable for the crystallization of cyanobacterial photosystem II. CMC measurements were based on established fluorescence techniques using pyrene and 8-anilinonaphthalene-1-sulfonate (ANS). We found an increase of the CMC with increasing PEG concentration according to ln(CMC/CMC0) = k(P)chi, where CMC0 is the CMC in the absence of PEG and k(P) is a constant that we termed the "polymer constant". In parallel, we measured the influence of PEG2000 on the surface tension of detergent-free buffer solutions. At PEG concentrations chi > 1% w/v, the surface pressure pi(s)(chi) = gamma(0) - gamma(chi) was found to depend linearly on the PEG concentration according to pi(s)(chi) = kappa chi + pi(s)(0), where gamma(0) is the surface tension in the absence of PEG. Based on a molecular thermodynamic modeling, CMC shifts and surface pressure due to PEG are related, and it is shown that k(P) = kappa c(n) + eta, where c(n) is a detergent-specific constant depending inter alia on the alkyl chain length n and eta is a correction for molarity. Thus, knowledge of the surface pressure in the absence of a detergent allows for the prediction of the CMC shift. The PEG effect on the CMC is discussed concerning its molecular origin and its implications for membrane protein solubilization and crystallization.
Issue Date: 2015
Date Available: 25-Oct-2017
DDC Class: 540 Chemie und zugeordnete Wissenschaften
Sponsor/Funder: DFG, SFB 429, Molekulare Physiologie, Energetik und Regulation primärer pflanzlicher Stoffwechselprozesse
DFG, SFB 498, Protein-Kofaktor-Wechselwirkungen in biologischen Prozessen
DFG, SFB 1078, Proteinfunktion durch Protonierungsdynamik
DFG, EXC 314, Unifying Concepts in Catalysis
BMBF, 031A154B, Basistechnologien Forschertandem: Nutzung von Sonnenenergie für die Bioelektrokatalyse - Entwicklung von Photo-Bioelektrodenstrukturen für die Synthese
Journal Title: Physical chemistry, chemical physics
Publisher: Royal Society of Chemistry
Publisher Place: Cambridge
Volume: 17
Issue: 17
Publisher DOI: 10.1039/c5cp00431d
Page Start: 11678
Page End: 11691
EISSN: 1463-9084
ISSN: 1463-9076
Notes: Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
Appears in Collections:FG Physikalische Chemie / Biophysikalische Chemie » Publications

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