High concentration solubility and stability of epsilon-poly-L-lysine in an ammonium-based ionic liquid: A suitable media for polypeptide packaging and biomaterial preparation


Packaging of structurally sensitive biomolecules such as proteins, peptides and DNA in non-aqueous media at ambient conditions with chemical and structural stability is important to explore the potential of such biomacromolecules as substrate for functional biomaterial design and for biotechnological applications. In this perspective, solubility, chemical and structural stability of epsilon-poly-L -lysine (epsilon-PL), a homopolypeptide produced by Streptomyces albulus in different ionic liquids (1Ls) namely 2-hydroxyethyl ammonium formate (2-HEAF), 2-hydroxyethyl ammonium acetate (2-HEAA), choline formate (Ch-Formate) and choline acetate (Ch-Acetate) was studied. Maximum solubility (15% w/v) of the homopolypeptide was observed in 2-HEAF and lowest was found in Ch-Formate (2% w/v). After regeneration of the dissolved polypeptide in the IL, the IL could be recycled and reused in the dissolution process. Unlike in other ILs, 3-15% w/v of epsilon-PL in 2-HEAF gave formation of a thixotropic thermoreversible soft gel. Molecular docking studies established favourable interactions of [2-HEA](+) cation over [Ch](+) with epsilon-PLindicating [2-HEA](+) as the most promising cation for the dissolution process. However, the role of the anions was also found to be important, which could lead to improvement in polypeptide solubility when combined to the selected cation. The findings demonstrate suitability of the ionic liquids for functionalization of polypeptides for biomaterial preparation. (C) 2018 Elsevier B.V. All rights reserved.



subject category

Biochemistry & Molecular Biology; Chemistry; Polymer Science


Sequeira, RA; Singh, N; Pereira, MM; Chudasama, NA; Bhattacharya, S; Sharma, M; Mondal, D; Prasad, K

our authors


KP thanks CSIR, New Delhi for overall financial support. RS thanks DST for DST-INSPIRE Fellowship, NS thanks UGC for SRF fellowship. Analytical and Environment Science Division & centralized instrument facility of the institute is acknowledged for overall analytical support. M.M.P. acknowledges the PhD grant (2740-13-3) and financial support from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior Capes. Dr. Mara G Freire is acknowledged for meaningful discussion and authors are grateful to Ms. Rita Teles for helping in carrying out some of the experiments. This is CSIR-CSMCRI communication No. 139/2017.

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