**Part 3**

**Stoichiometry in Lipids and Polymers Architecture** 

132 Stoichiometry and Research – The Importance of Quantity in Biomedicine

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**6** 

*1USA 2UK* 

**Lipid Composition in Miscible** 

Walter F. Schmidt1\*, Michael A. Crawford2, Swati Mookherji1 and Alva D. Mitchell1

*2Imperial College, Department of Cancer and Surgery,* 

*1Agriculture Research Service, United States Department of Agriculture, Beltsville, MD,* 

Lipids play a vital role in the architecture of cell membranes. About one third of the known cellular proteins are located in the membrane lipid and these are largely the transporters, signalers, receptors and defense systems. The fatty acid component in membranes across species and in different cell types is species, organ and sub cellular specific. In human cell types, the inner cell membrane is dominated by arachidonic acid whilst that of the photo receptor and neural synapse is strikingly rich in docosahexaenoic acid. The biophysical basis

Differences in lipid composition and lipids membrane packing must inevitably affect cell function. Dietary deficiency of docosahexaenoic acid (DHA) in pregnant rats has been shown to reduce fetal neurogenesis and neuronal cell migration [19]. Deficiency in infants can restrict visual and cognitive development [18]. Close structural analogs of DHA do not displace DHA from active sites even when such analogs are present at higher concentrations than DHA in the diet or in cell systems [3]. Thus the chemical structure of lipids at active sites is conserved at the molecular level by dietary lipids but lipids generated biochemically

NMR spectroscopy, X-ray crystallography, and computational chemistry are essential tools in discriminating the molecular shape of biomolecules. Although NMR experiments using Deuterium-Labeled NMR have long been used to probe phospholipid bilayers [17], far fewer experiments yielding structural information have been generated for lipids than for proteins and carbohydrates. Natural abundance 13C-NMR experiments with DHA demonstrated that highly unsaturated lipids pack more closely than more saturated lipids [2]. However, identifying the specific inter-molecular sites critical to lipid packing was not discernable.

Discrete chemical compositions of mixtures at the molecular level within definable unit cell molar volumes have been reported for stearic acid (SA) in the presence of structurally

**1. Introduction** 

 \*

Corresponding Author

for this molecular specificity in not understood.

somehow do not displace or dilute them.

*Division of Reproductive Physiology, Obstetrics and Gynecology, London,* 

**and Immiscible Phases** 
