Premium
Effects of additives on surfactant phase behavior relevant to bacteriorhodopsin crystallization
Author(s) -
Berger Bryan W.,
Gendron Colleen M.,
Lenhoff Abraham M.,
Kaler Eric W.
Publication year - 2006
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.062370506
Subject(s) - crystallization , bacteriorhodopsin , chemistry , pulmonary surfactant , cloud point , isothermal titration calorimetry , phase (matter) , virial coefficient , polyethylene glycol , chromatography , octyl glucoside , micelle , chemical engineering , analytical chemistry (journal) , membrane , thermodynamics , organic chemistry , aqueous solution , biochemistry , physics , engineering
The interactions leading to crystallization of the integral membrane protein bacteriorhodopsin solubilized in n‐octyl‐β‐D‐glucoside were investigated. Osmotic second virial coefficients (B 22 ) were measured by self‐interaction chromatography using a wide range of additives and precipitants, including polyethylene glycol (PEG) and heptane‐1,2,3‐triol (HT). In all cases, attractive protein–detergent complex (PDC) interactions were observed near the surfactant cloud point temperature, and there is a correlation between the surfactant cloud point temperatures and PDC B 22 values. Light scattering, isothermal titration calorimetry, and tensiometry reveal that although the underlying reasons for the patterns of interaction may be different for various combinations of precipitants and additives, surfactant phase behavior plays an important role in promoting crystallization. In most cases, solution conditions that led to crystallization fell within a similar range of slightly negative B 22 values, suggesting that weakly attractive interactions are important as they are for soluble proteins. However, the sensitivity of the cloud point temperatures and resultant coexistence curves varied significantly as a function of precipitant type, which suggests that different types of forces are involved in driving phase separation depending on the precipitant used.