A unifying T m diagram for phosphatidylethanolamines with sn -1 C 20 saturated and sn -2 C 18 unsaturated acyl chains

Huang, Chunbo; Wang, G.; Huo, Lin; Li, S.

doi:10.1016/s0005-2736(98)00092-3

Cited by 6 publications

(4 citation statements)

References 14 publications

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“…The mixed-chain PE that can, upon unsaturation, convert into a higher T m species has the following structural characteristics: 1) the sn-2 acyl chain contains at least two methylene-interrupted cis ⌬-bonds; 2) the number of consecutive methylene units in the upper chain segment is no fewer than that in the lower chain segment; 3) the ⌬-bond to be further incorporated into the unsaturated sn-2 acyl chain must be added in the lower chain segment in the direction toward the methyl terminus. Furthermore, for mixed-chain PE with 20 carbon atoms in the sn-2 acyl chain, it is interesting to note that only 3 lipids such as C (20):C(20:3⌬ 11,14,17 )PE and C (20):C(20:4⌬ 8,11,14,17 )PE exhibit higher T m values than their 6 precursors as shown calorimetrically in the present and previous studies (8,23). The significance of the down and up T m profile is that it means the polyunsaturated 3 lipid with its multiple ⌬-bonds positioning near the chain terminus is highly ordered.…”

Section: Discussionsupporting

confidence: 79%

Effects of Various Numbers and Positions of cisDouble Bonds in the sn-2 Acyl Chain of Phosphatidylethanolamine on the Chain-melting Temperature

Wang

Huo

et al. 1999

Journal of Biological Chemistry

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In an attempt to investigate systematically the effects of various single and multiple cis carbon-carbon double bonds in the sn-2 acyl chains of natural phospholipids on membrane properties, we have de novo synthesized unsaturated C 20 fatty acids comprised of single or multiple methylene-interrupted cis double bonds. Subsequently, 15 molecular species of phosphatidylethanolamine (PE) with sn-1 C 20 -saturated and sn-2 C 20 -unsaturated acyl chains were semi-synthesized by acylation of C 20 -lysophosphatidylcholine with unsaturated C 20 fatty acids followed by phospholipase D-catalyzed base-exchange reaction in the presence of excess ethanolamine. The gel-to-liquid crystalline phase transitions of these 15 mixed-chain PE, in excess H 2 O, were investigated by high resolution differential scanning calorimetry. In addition, the energy-minimized structures of these sn-1 C 20 -saturated/sn-2 C 20 -unsaturated PE were simulated by molecular mechanics calculations. It is shown that the successive introduction of cis double bonds into the sn-2 acyl chain of C(20):C(20)PE can affect the gel-to-liquid crystalline phase transition temperature, T m , of the lipid bilayer in some characteristic ways; moreover, the effect depends critically on the position of cis double bonds in the sn-2 acyl chain. Specifically, we have constructed a novel T m diagram for the 15 species of unsaturated PE, from which the effects of the number and the position of cis double bonds on T m can be examined simultaneously in a simple, direct, and unifying manner. Interestingly, the characteristic T m profiles exhibited by different series of mixed-chain PE with increasing degree of unsaturation can be interpreted in terms of structural changes associated with acyl chain unsaturation.Most naturally occurring diacyl phospholipids in eukaryotic cell membranes are of a mixed acyl chain variety, meaning that the fatty acids esterified at the sn-1 and sn-2 positions of the glycerol backbone are originated primarily in vivo from saturated and unsaturated fatty acyl-CoA, respectively. Since the chemical composition of fatty acids can vary greatly in terms of the acyl chain length, the degree of unsaturation, and the position of cis carbon-carbon double bonds (⌬-bonds), 1 membrane phospholipids are structurally an extremely diverse group of amphipathic molecules. In a given type of cell, membrane phospholipids may amount to several hundreds of distinctive chemical species. Despite the bewildering diversity, the basic motif of most unsaturated fatty acyl chains is surprisingly simple, viz. in the sn-2 acyl chain, the cis carboncarbon double bonds are invariably separated by a three-carbon unit comprised of a methylene group (-CH 2 -) sandwiched by two olefinic carbons. The biochemical significance of this regular methylene-interrupted interval is, however, not clear.Although it has long been known that mixed-chain diacyl phospholipids in aqueous media can uniquely assemble into a two-dimensional sheet-like structure called the lipid bilayer, progress is non...

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Section: Discussionsupporting

confidence: 79%

Effects of Various Numbers and Positions of cisDouble Bonds in the sn-2 Acyl Chain of Phosphatidylethanolamine on the Chain-melting Temperature

Wang

Huo

et al. 1999

Journal of Biological Chemistry

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“…For instance, the thermodynamic parameters associated with the gel-to-liquid crystalline phase transition of lipid bilayers prepared from three series of PtdEth are shown in Table 2 (29). More recently, the total numbers of different species of sn-1 saturated/sn-2 unsaturated PtdEth originated from the common precursors of C (20):C(18)PtdEth and C (20):C(20)PtdEth have been extended in this laboratory to 10 and 15 molecular species, respectively (24,25). In this presentation, I shall limit my dis- Figure 14.…”

Section: The Structure and The Chain-melting Behavior Of Phospholipidmentioning

confidence: 96%

Mixed‐chain phospholipids: Structures and chain‐melting behavior

Huang

2001

Lipids

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It has long been established that diacyl phospholipids isolated from animal cell membranes are predominantly of a mixed-chain variety, meaning that the sn-1 and sn-2 acyl chains are saturated and unsaturated acyl chains, respectively. In general, monoenoic and dienoic acids are found in the sn-2 acyl chain of phosphatidylcholine (PtdCho), whereas polyenoic acids are in phosphatidylethanolamine (PtdEth). These unsaturated chains contain only cis-double bonds, which are always methylene-interrupted. In recent years, the structures and the chain-melting behavior of mixed-chain PtdCho and PtdEth have been systematically studied in this laboratory. Specifically, we have examined the effects of chain unsaturation of the sn-2 acyl chain on the phase transition temperature (Tm) of many PtdCho and PtdEth by high-resolution differential scanning calorimetry (DSC). The Tm values, for instance, obtained from all-unsaturated mixed-chain PtdEth derived from a common precursor can be grouped together according to their chemical formula to form a Tm-diagram. Hence, all the Tm values can be compared simply, systematically, and simultaneously using the Tm-diagram. In addition, the energy-minimized structures of mixed-chain phospholipids containing different numbers/positions of methylene-interrupted cis-double bonds have been simulated by molecular mechanics calculations (MM). In this review, the results of our MM and DSC studies carried out with various mixed-chain phospholipids are summarized. In addition, we emphasize that the combined approach of MM and DSC yields unique information that can correlate the various Tm-profiles seen in the Tm-diagram with the structural variation of mixed-chain lipids as caused by the introduction of different numbers/positions of methylene-interrupted cis-double bonds.

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“…So, T m is an important physical parameter that characterizes the state of aggregation of phospholipids in vesicles. 43 In small vesicles, where bilayer curvature is high, the packing of the phospholipid hydrocarbon chains is less important in comparison to large vesicles where the surface is locally more planar. Hence the formation of an organized (i.e.…”

Section: A Evidence Of Ptmc Crystallization In Polymersomesmentioning

confidence: 99%

Temperature responsive poly(trimethylene carbonate)-block-poly(l-glutamic acid) copolymer: polymersomes fusion and fission

et al. 2010

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A unifying T m diagram for phosphatidylethanolamines with sn -1 C 20 saturated and sn -2 C 18 unsaturated acyl chains

Cited by 6 publications

References 14 publications

Effects of Various Numbers and Positions of cisDouble Bonds in the sn-2 Acyl Chain of Phosphatidylethanolamine on the Chain-melting Temperature

Effects of Various Numbers and Positions of cisDouble Bonds in the sn-2 Acyl Chain of Phosphatidylethanolamine on the Chain-melting Temperature

Mixed‐chain phospholipids: Structures and chain‐melting behavior

Temperature responsive poly(trimethylene carbonate)-block-poly(l-glutamic acid) copolymer: polymersomes fusion and fission

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