Three series of pyrene-labeled polypeptides, namely, poly(L-lysine) (PyPLL), poly(L-glutamic acid) (Py-PLGA), and poly(D,L-glutamic acid) (Py-PDLGA), were studied in dimethyl sulfoxide (DMSO) by monitoring their ability to form an excimer between an excited and a ground-state pyrene. The effect that the charges of protonated Py-PLL (Py-PLL center dot HCl) and deprotonated Py-PLGA (Py-PLGNa) and PyPDLGA (Py-PDLGNa) had on their conformation and dynamics was assessed by monitoring their fluorescence. The fluorescence decays were analyzed according to the fluorescence blob model (FBM) to determine Nblob, which is the number of structural units in a blob, and kblob, which is the rate constant for diffusive encounters between structural units and their side chains inside a blob. FBM analysis indicated that the blob size for Py-PLGA and Py-PDLGA was unaffected by the presence of anionic charges, yielding Nblob values of 10.3 +/- 1.7 and 18.2 +/- 1.1 glutamic acid units, respectively. These Nblob values matched the values found for their uncharged counterparts. Molecular mechanics optimizations (MMOs) were then applied to determine the theoretical Nblobth value that could be obtained if Py-PLGA adopted the conformation of a random coil, a polyproline type II helix, a 310-helix, or an alpha-helix. The agreement found between the N-blob value of 17.9 +/- 1.1 for protonated PLGA and deprotonated PLGNa and the N-blob(th) of 19 found for 310-helical conformation suggested that this was the conformation adopted by the PLGAs in DMSO. Py-PLL center dot HCl was studied in a similar manner, yielding an N-blob value of 14.3 +/- 1.3 lysines, which suggested a coiled conformation according to MMOs. Comparison of k(blob) between charged and neutral polypeptides demonstrated that the presence of charges slowed the dynamics experienced by the amino acids. Because the polypeptide blobs appeared to have features in terms of their size and dynamics that were similar to those of foldons, this study further supports the notion that blobs and foldons might be identical objects.