Page - (000238) - in Biomedical Chemistry: Current Trends and Developments

depending on various parameters, such as the amino acid composition of the structure and its stability under different environmental conditions, as well as on parameters of the target cell such as membrane composition and structural features (Fig. 3.1.11). As the factors that contribute to peptide-lipid interactions are beginning to be understood, many opportunities remain for the organic chemist to design new systems that address some of these issues. Eukaryotic plasma membranes contain phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and sphingomyelin, and are enriched in cholesterol in contrast to bacterial plasma membranes, which are often composed of one major lipid (Pretzel, 2013). Besides the negatively-charged phosphatidylserine, none of the aforementioned phospholipids has a net charge, meaning eukaryotic membranes are generally neutral. In contrast, prokaryotic membranes are enriched in negatively charged lipids such as in Gram-positive bacteria, which contain the negatively charged teichoic and teichuronic acids in their envelope (Yeaman & Yount, 2003). Combined with differences in the electrochemical gradients of cells from different organisms, differences in the membrane environment and the remodeling of the host cell membrane by intracellular parasites (Hsiao, 1991), these factors could explain why AMPs discriminate between microbial cells and host cells, or between parasites and mammalian cells (Pretzel, 2013; Yeaman & Yount, 2003). Figure 3.1.11: Interrelationship among structural determinants in antimicrobial peptides. Fundamental composition and amino acid sequence influence not only the biochemical properties of the peptide [e.g. charge (Q), amphipathicity (A), and hydrophobicity (H)], but also