pepinfo produces information on amino acid properties (size, polarity, aromaticity, charge etc). Hydrophobicity profiles are also available and are useful for locating turns, potential antigenic peptides and transmembrane helices. Various algorithms are employed including the Kyte and Doolittle hydropathy measure - this curve is the average of a residue-specific hydrophobicity index over a window of nine residues. When the line is in the upper half of the frame, it indicates a hydrophobic region, and when it is in the lower half, a hydrophilic region.