Figure 5.

Intrinsic size parameters derived from [Pep+2H]²⁺ ions (pentapeptides or longer). The intrinsic size parameters have been organized into regions for amino acid residues and residue modifications. The amino acid residues are further grouped into subclassifications of amino acids on the basis of similarities in the side chain. Error bars represent one standard deviation from the mean. Space-filling models of the atomic structures for amino acid residues and the Pal/Am modifications are supplied to give a sense of scale with differences in size and polarity. Gray, blue, red, yellow, and white balls represent carbon, nitrogen, oxygen, sulfur, and hydrogen atoms, respectively.