title: Thermal stability of lipid-depleted purple membranes at neutral and low pH values.
abstract: Differential scanning calorimetry was used to compare the thermal behavior of native and delipidated purple membrane fragments at pH values corresponding to purple, blue and acid-purple forms. At neutral pH, delipidation results in a 2.5- to 3-times increase in the cooperativity of the denaturational transition, accompanied by a minor increase in its temperature. At pH values below 5 the delipidated membranes exhibit considerably higher thermal stability than the native membranes. The reversible predenaturational transition observed in the native state is not detectable upon delipidation. There is no strict correlation between color changes upon acidification and deionization of either native or delipidated purple membranes and their thermal stability.
authors.affiliation: Central Laboratory of Biophysics, Bulgarian Academy of Sciences, Sofia.
authors.forename: S G
authors.initials: SG
authors.lastname: Taneva
authors.forename: R
authors.initials: R
authors.lastname: Koynova
authors.forename: B
authors.initials: B
authors.lastname: Tenchov
mesh_terms: D001436:Bacteriorhodopsins / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D004355:Drug Stability; D019617:Halobacterium salinarum / Q000378:metabolism; D006863:Hydrogen-Ion Concentration
chemical_list: D001436:Bacteriorhodopsins