Fluorine-19 nuclear magnetic resonance studies of lipid fatty acyl chain order and dynamics in Acholeplasma laidlawii B membranes. A direct comparison of the effects of cis- and trans-cyclopropane ring and double-bond substituents on orientational order

Abstract

The hydrocarbon chain orientational order parameters of membranes of Acholeplasma laidlawii B, enriched with large quantities of fatty acids containing either a cis or a trans cyclopropane ring or a cis or trans double bond, plus small quantities of one of an isomeric series of monofluoropalmitic acids, were determined via fluorine-19 nuclear magnetic resonance spectroscopy over a range of temperatures spanning the corresponding gel to liquid-crystalline phase transitions (determined via differential scanning calorimetry). Membrane orientational order profiles in the liquid-crystalline state were generally similar, regardless of the particular fatty acid structure present, showing a region of relatively constant order preceding a region of progressively decreasing order toward the methyl terminus of the acyl chain. In the gel state, the order profiles in the presence of either a trans cyclopropane ring or trans double-bond substituent were similar and were characterized by a pronounced head to tail gradient of order at temperatures just below the lipid phase transition, while at temperatures far below the lipid phase transition this gradient was less pronounced, all chain positions showing a more uniformly high degree of orientational ordering. In the gel state, the order profiles in the presence of either a cis cyclopropane ring or a cis double-bond substituent were also similar but were highly unusual in that order first increased and only then subsequently decreased toward the acyl chain methyl terminus. In addition, the substituents in the cis configuration, whether a cyclopropane ring or a double bond, were overall more disordered in the gel state than the corresponding substituents in the trans configuration.(ABSTRACT TRUNCATED AT 250 WORDS)

Involvement of Cyclopropane Fatty Acids in the Response of Pseudomonas putida KT2440 to Freeze-Drying

“…We found that viability was affected to a certain extent under all conditions compared here but that disaccharides, e.g., trehalose, maltose, and lactose, were the best lyoprotectants. This finding is in agreement with observations reported in experiments with other microorganisms (Escherichia coli, Bacillus thuringiensis, and Pseudomonas chlororaphis) that were protected during lyophilization by disaccharides (22,23,28). The molecular mechanism behind the protective effect of disaccharides during freeze-drying is unknown, although it has been suggested that these chemicals protect membrane integrity by replacing water molecules in the membrane during the freeze-drying process (23).…”

Differential Effects of Permeating and Nonpermeating Solutes on the Fatty Acid Composition of Pseudomonas putida

“…Further reductions in matric water potential could lower the liquid crystalline-tohexagonal phase transition temperature. By increasing the amount of trans unsaturated fatty acids, P. putida may raise this transition temperature (7,29,50) and prevent the formation of hexagonal II phases, which are favored by cis monounsaturated fatty acids, and thus again maintain the membrane in a liquid crystalline phase.…”

Cellular Envelopes and Tolerance to Acid pH in Mesorhizobium loti

“…A similar increase of the percentage of 19:0 cy fatty acid with the increase of the acidity of the medium was shown by Ballen et al [2] in R. tropici UMR 1899 and UMR 5050 strains. Mac Donald et al [25] have suggested that cyclopropane fatty acids increase in general the organizational stability of membranes and play a protective role against physiological stress. In E. coli, Grogan and Cronan [12] have shown that cyclopropane fatty acid synthase expression was enhanced by low pH.…”