Acyl lipid, building block

Phospholipids are the major lipid building blocks most membranes and their molecules comprise of a hydrophobic (acyl chain) and a hydrophilic (polar) head group. The relative size of the hydrophobic tails and hydrophilic head of the molecule characterizes the molecular shape and determines the structure of the molecular assemblies in contact with w ater. Molecules with polar and non-polar regions (PC, PS, PI, Sphm) of equal size have a cylindrical shape and form lipid bilayers. Molecules that have a larger non-polar region are cone-shaped (PE, PA, Choi, Car), and form reversed micelles, in contact to water. When the polar region is larger (lysophospholipids) the molecule assembles an inverted cone and form micelles. Fig. (8). 

Figure 3 Different approaches for the introduction of lipid functionalities, here exemplified via the farnesyl group, into peptides. (A) Lipidated amino acid building blocks. (B) Substitution of bromoalanine with a nucleophile. (C) Alkylation or acylation of a free thiol functionality of a cysteine. (D) Conjugate addition of a nucleophile (e.g., farnesylthiolate) to a dehydroalanine. (E) Conjugate addition of a nucleophile to aziridine-2-carboxylic acid containing...

Figure 6.7 Representative two-dimensional mass spectrometric analyses of triacylglycerol species in hepatic lipid extracts of mice. Neutral loss scans (NLS) of all naturally occurring fatty acyl chains (i.e., the building blocks of TAGs) of mouse liver lipid extract were acquired to determine the identities of individual lithiated TAG molecular ion, deconvolute isomeric species, and quantify individual TAG species by comparisons with a selected internal standard (i.e., T17 l TAG atm/z 849.6 as lithium adduct, shown in NLS268). Collision activation was performed with collision energy at 32 eV and collision gas pressure at 1 mTorr on a QqQ-type mass spectrometer (TSQ Vantage, Thermo Fisher Scientific, San Jose, CA, USA). All displayed mass spectral traces are normalized to the base peak in each trace.

Fatty acids are important building blocks for various cellular complex lipids (Figure 7). For simplicity, the pathways for incorporation of fatty acids into these lipids are outlined only briefly. More details can be found in any good biochemistry text. In most cases, fatty acyl-CoA and not free... 

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