Table 1.

Sequences of oligopeptide modules and structures of Gd(III)-chelates.

Peptide	Sequences of Co-Assembling Modules	Mw (Da)	Z (e)	Vm (Å3)
1	formyl-EFEAEAEAEW-carboxyl	1,235.7	654	1416.6
2	formyl-OFOAOAOAOW-amide	1,162.7	624	1426.6
3	[Gd(do3a)]GGGOFOAOAOAOW-amide	1,848.0	948	1877.7
3′	[Gd(do3a)]GGG-amide	730.2	340	475.9
3		3′

Modular material assembly is achieved by pairing a positive module (2 or 3) with a negative module (1). The free Gd(III)-chelate, 3′, carries zero net charge. Positively charged amino acids are in red, negatively charged amino acids are in blue, and neutral amino acids are in black. A, alanine; E, glutamic acid; F, phenylalanine; G, glycine; O, ornithine; W, tryptophan. Z is a number of electrons in each peptide; V_m is a molecular volume of each module. V_m is calculated by summing the standard volumes of various functional groups in peptides and Gd(III)-chelate using the Voronoi approximation.¹⁹