UCR researchers have developed novel compstatin peptides with polar amino acid extensions at the N-terminus and PEGylated extensions at the C-terminus. The new peptides have the following advantages compared to previously known compstatin peptides: (i) highly improved aqueous solubility while maintaining high inhibitory potency, and (ii) higher inhibitory efficacy against complement system activation in a human retinal pigmented epithelial cell-based assay that mimics the pathobiology of age-related macular degeneration. The combined solubility and inhibitory potency and efficacy properties render the new peptides excellent candidates to become therapeutics for the treatment of age-related macular degeneration. A potent and highly soluble compstatin peptide shown in surface representation with an 8 PEG block C-terminal extension displayed in stick form. The surface of the compstatin analog is colored according to amino acid properties: gray for hydrophobic, green for polar neutral, blue for polar positively charged, red for polar negatively charged, yellow for cysteines of the disulfide bridge, and brown for glycine. The molecular image is generated using three-dimensional coordinates from a molecular dynamics simulation trajectory.