Antimicrobial Peptides: Their Role as Infection-Selective Tracers for Molecular Imaging

Figure 2

Comparative lipid architecture of microbial and human cytoplasmic membranes. Cytoplasmic membranes of bacterial (Escherichia coli, Staphylococcus aureus, or Bacillus subtilis) and fungal (Candida albicans) pathogens are compared with that of the human erythrocyte in relative composition and distribution between inner and outer membrane leaflets. Membrane constituents ranging from anionic (left) to neutral (right) are CL, PG, PE, PC, SM, and sterols (cholesterol or ergosterol, ST). Note the marked difference among microbial pathogens and human erythrocytes resides in the phospholipid composition and asymmetry. These differences are believed to account for the selective antimicrobial peptide affinity for microbial versus host cells to the extent that it exists for a given antimicrobial peptide. Keys: open, E. coli; horizontal hatching, S. aureus; shaded, B. subtilis; checkered, C. albicans; solid, human erythrocyte (adapted from [9]).