These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Thermotropic characterization of the 2-O-acyl,polyprenyl alpha-D-glucopyranoside isolated from palmitate-enriched Acholeplasma laidlawii B membranes.
    Author: Lewis RN, Yue AW, McElhaney RN, Turner DC, Gruner SM.
    Journal: Biochim Biophys Acta; 1990 Jul 09; 1026(1):21-8. PubMed ID: 2378878.
    Abstract:
    The thermotropic phase behavior of a monoacylated neutral glucolipid (2-O-acyl,polyprenyl alpha-D-glucopyranoside), isolated from palmitate-enriched Acholeplasma laidlawii B membranes, was studied by differential scanning calorimetry, infrared spectroscopy and X-ray diffraction. When equilibrated at low temperatures, aqueous dispersions of this lipid form an ordered, crystal-like lamellar gel phase which transforms to an inverted hexagonal phase at temperatures near 65 degrees C upon heating. However, upon cooling from high temperatures, the inverted hexagonal phase remains stable down to temperatures near 45 degrees C. Further cooling first results in the formation of a metastable lamellar liquid crystalline phase at temperatures near 35 degrees C and then a metastable gel phase at lower temperatures. The metastable gel phase, if immediately reheated at a fast scan rate, undergoes a gel/liquid-crystalline phase transition at temperatures near 33 degrees C. These results indicate that this monoacylated glucolipid exhibits its gel/liquid-crystalline phase transition and its lamellar/non-lamellar phase transition at considerably lower temperatures than does the monoglycosyldiacylglycerol formed under the same conditions. When cultured in media enriched in 'high-melting' fatty acids, Acholeplasma laidlawii B synthesizes large quantities of the 2-O-acyl,polyprenyl alpha-D-glucopyranoside (up to 60 mol%) mainly at the expense of the monoglucosyldiacylglycerol (the only other nonbilayer-forming liquid normally found in the cell membrane of this organism). We thus suggest that the biosynthesis of this novel glucolipid, in response to the biosynthetic incorporation of high-melting exogenous fatty acids, is an adaptive response designed to maintain a predominantly liquid-crystalline membrane lipid bilayer at the growth temperature, while retaining the high proportion of nonbilayer-forming glucolipid species characteristic of A. laidlawii B cells cultured under these conditions.
    [Abstract] [Full Text] [Related] [New Search]