Crystal structure, fatty acid

Because of its cylindrical shape and hydrophobic character, cholesterol is an important component of the membranes of animal cells. Its rigid structure decreases membrane fluidity, but it also inhibits the crystallization of fatty acid side chains of the membrane lipids and it acts as a sort of membrane plasticizer. 

Electron diffraction studies are usually limited to transferred films (see Chapter XV), One study on Langmuir films of fatty acids has used cryoelectron microscopy to fix the structures on vitrified water [179], Electron diffraction from these layers showed highly twinned structures in the form of faceted crystals. 

Transmission electron microscopy (TEM) can resolve features down to about 1 nm and allows the use of electron diffraction to characterize the structure. Since electrons must pass through the sample however, the technique is limited to thin films. One cryoelectron microscopic study of fatty-acid Langmuir films on vitrified water [13] showed faceted crystals. The application of TEM to Langmuir-Blodgett films is discussed in Chapter XV. 

Curry, S., Mandelkow, H., Brick, P. and Franks, N. (1998) Crystal structure of human serum albumin complexed with fatty acid reveals an asymmetric distribution of binding sites. Nature Structural Biology 5, 827-835. 

Scheme 2 shows the biosynthesis ofN-(3-oxooctanoyl)-L-homoserine lactone by Tral protein from Agrobacterium using 3-oxooctanoyl-ACP, derived from fatty acid metabolism, as a substrate [29, 33]. Recently, the first crystal structure of a LuxI protein homologue [34] has provided new insights into the function of AHL synthases which will aid the design of novel inhibitors of AHL biosynthesis. 

I. Petitpas, T. Grime, A. A. Bhattacharya, S. Curry, Crystal Structures of Human Serum Albumin Complexed with Monounsaturated and Polyunsaturated Fatty Acids , J. Mol. Biol. 2001, 314, 955-960. 

Source Pemble CP IV, Johnson LC, KridelSJ, LowtherWT. Crystal structure of the thioeste-rase domain of human fatty acid synthase inhibited by Orlistat, Nature Structural Molecular Biology 14 704-709 (2007). 

Protein biotinylation is catalyzed by biotin protein ligase (BPL). In the active site of the enzyme, biotin is activated at the expense of ATP to form AMP-biotin the activated biotin can then react with a nucleophile on the targeted protein. BPL transfers the biotin to a special lysine on biotin carboxyl carrier protein (BCCP), a subunit of AcCoA carboxylase (Scheme 21). Biotinylation of BCCP is very important in fatty acid biosynthesis, starting the growth of the fatty acid with AcCoA carboxylase to generate malonyl-CoA. Recently the crystal structures of mutated BPL and BCCP have been solved together with biotin and ATP to get a better idea of how the transfer fiinctions. ... 

Fir.. 7. Structure of dibasic fatty acid COOH 04H6 COOH. Long hydrogen bonded chains are formed in the c direction in the crystal... 

Derivatives of UP. Much recent work has involved interpreting substituent effects on the solid-state reactions of UP, and more than 60 derivatives have been prepared for this purpose. Some substitutions drastically alter the packing pattern within crystal layers, which makes their influence difficult to interpret. This is particularly true when the parity of the carbon chain length of the constituent fatty acids is changed from odd to even. In the discussion below we focus on the following substitutions of UP which give the same layer structure and are thus easier to understand ... 

Molecular Replacement. The tertiary structure of crystalline ALBP was solved by using the molecular replacement method incorporated into the XPLOR computer program (Brunger et al., 1987). The refined crystal structure of myelin P2 protein without solvent and fatty acid was used as the probe structure throughout the molecular replacement studies. We are indebted to Dr. A. Jones and his colleagues for permission to use their refined P2 coordinates before publication. 

DCA is the first bile acid whose inclusion ability was confirmed in the crystalline state. During the last century many research groups dealt with the inclusion compounds of DCA with various guest molecules, such as aliphatic, aromatic and alicyclic hydrocarbons, alcohols, ketones, fatty acids, esters, ethers, nitriles, peroxides and amines, and so on [2], In 1972, Craven and DeTitta first reported the exact crystal structure of DCA with acetic acid [3], Subsequent crystallographic studies made clear that most of DCA inclusion crystals have bilayer... 

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