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. Author manuscript; available in PMC: 2011 Dec 30.
Published in final edited form as: Adv Drug Deliv Rev. 2010 Apr 14;62(15):1524–1529. doi: 10.1016/j.addr.2010.04.001

Fig. 4.

Fig. 4

Schematic representation of the a multifunctional biopolymer composed of fusogenic peptide, DNA condensing and endosomyltic motif (DCE), nuclear localization signal, cathepsin substrate and targeting motif. In the RRX1RRX2HHX3HHX4 domain, residue X1 was designed to be valine in order to generate RVRR sequences along the DCE unit to enhance biodegradability by ubiquitous intracellular furin enzyme. This was intended to promote biodegradation of the cationic domain intracellularly resulting in less biopolymer related toxicity. Residues X2 and X4 are designed to be serine (S) and threonine (T). T and S were selected to increase the solubility of the biopolymer and yield of production. Residue X3 in the first and second repeating unit is R and in the third repeating unit is H. This is to incorporate an intrinsic histag into the biopolymer sequence which facilitates its purification via Ni-NTA chromatography. Reproduced with permission from [29].