Acyl chain structure

Table I CD, Rocking Modes and Acyl Chain Structure (Maroncelli, Strauss, and Snyder, J. Phys. Chem. 89, 4390 (1985))...

CL forms both [M-H] and [M-2H]2 ions and its fatty acid moiehes can be deduced from the product ion spectrum [33,56,61]. Complete structural analysis of CL, i.e., identification of the positions of the fatty acids in the molecule, requires the use of an ion trap instrument and multiple fragmentation steps [62,63]. Quantification of the positional isomers is not straightforward, however, due to acyl chain structure-dependent fragmentation efficiency [64]. 

Applications of fluorine NMR m biochemistry, Gerig, J T In Biomedical Aspects of Fluorine Chemistry Filler, R, Kobayashi, Y, Eds, Kodansha Tokyo, 1982, pp 163-189 RIO Fatty acyl chain structure, orientational order, and the lipid phase transition m Acholeplasma laidlawii membranes A review of recent fluorine-19 NMR studies, MacDonald, P M, Sykes, B D, McElhaney, R N Can J Biochem Cell Biol 1984, 62, 1134-1150 (47 references)... 

Bauerle and Seelig [395] studied the structural aspects of amlodipine (weak base, primary amine pKa 9.26 [162]) and nimodipine (nonionizable) binding to phospholipid bilayers, using NMR, microcalorimetry, and zeta-potential measurements. They were able to see evidence of interactions of amlodipine with the cis double bond in the acyl chains. They saw no clear evidence for (=P—O- 1 H N—) electrostatic interactions. 

Seelig J. and Seelig A. (1974). Dynamic structure of fatty acyl chains in a phospholipid bilayer measured by DMR, Biochemistry, 13, 4839-4845. 

Fig. 2.—Chemical structure of lipid A of the Escherichia coli Re mutant strain F515. The hydroxyl group at position 6 constitutes the attachment site of Kdo. The numbers in circles indicate the number of carbon atoms present in the fatty acyl chains. The 14 0(3-OH) residues possess the (Reconfiguration. The glycosylic phosphate group may be substituted by a phosphate group (see Table I) (46,65,69).

The anthroyl fluorophore is located deep in the hydrophobic region of the lipid bilayer corresponding to the C9-C16 segment of the acyl chains. The excited-state lifetime, associated with a non-structured fluorescence spectrum with a maximum at 460 nm (to be compared to those shown in Figure 7.6), can be accounted for by interaction of the fluorophore with water molecules that diffuse across the bilayer. Information is thus obtained on the permeability of lipid bilayers to water and its modulation by cholesterol. 

Figure 12.11 Phosphoglyceride structure. The members of this group are derivatives of the parent compound, l,2-diacyl-src-glycerol-3-phosphate (phosphatidic acid) in which X is a hydrogen atom. This is replaced by either an amino alcohol or a polyhydroxy residue. In phosphoglycerides derived from animal tissues R1 is usually a saturated acyl chain of between 16 and 20 carbon atoms and R2 is usually unsaturated. Polyunsaturated acyl chains containing 16 or 18 carbon atoms predominate in leaf phosphoglycerides and those of bacterial origin are often more complex.

The properties of membranes commonly studied by fluorescence techniques include motional, structural, and organizational aspects. Motional aspects include the rate of motion of fatty acyl chains, the head-group region of the phospholipids, and other lipid components and membrane proteins. The structural aspects of membranes would cover the orientational aspects of the lipid components. Organizational aspects include the distribution of lipids both laterally, in the plane of the membrane (e.g., phase separations), and across the membrane bilayer (phospholipid asymmetry) and distances from the surface or depth in the bilayer. Finally, there are properties of membranes pertaining to the surface such as the surface charge and dielectric properties. Fluorescence techniques have been widely used in the studies of membranes mainly since the time scale of the fluorescence lifetime coincides with the time scale of interest for lipid motion and since there are a wide number of fluorescence probes available which can be used to yield very specific information on membrane properties. 

The motional characteristics of interest are typically those governed by the phospholipid fatty acyl chains and head-group region and the neutral lipid or protein components of membranes. Rotational motion can be subdivided into a structural component, the order or degree of orientational constraint,... 

M. Straume and B. J. Litman, Equilibrium and dynamic structure of large, unilamellar, unsaturated acyl chain phosphatidylcholine vesicles. Higher order analysis of 1,6-diphenyl-... 

---