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Study of the polyribosyl-ribitol-phosphate precipitation mechanism by salts and organic solvents.
Int J Biol Macromol 2019; 140:102-108IJ

Abstract

Precipitation has been widely applied to purification and fractionation of biological macromolecules. Several physical-chemical factors contribute to the destabilization of those solutions, such as the nature of solvent employed, presence of salts, temperature, and concentration of the macromolecule. In the case of charged biopolymers, electrostatic forces are the major contributors to their stability in solution. However, the role of each variable and the exact mechanism of precipitation are not completely understood yet. The aim of this work was to study the precipitation of polyribosyl-ribitol-phosphate (PRP, a linear homogeneous anionic biopolymer) in presence of salts and non-solvents, in order to contribute to the elucidation of its precipitation mechanism. The solvents tested (acetone, ethanol, and isopropanol) presented distinct dielectric constants. The salts used (NH4Cl, NaCl, KCl, MgCl2, and CaCl2) differ by their cations. For each salt concentration, the solvent fraction that induces precipitation was identified and the dielectric constant of the bulk solution was calculated. Precipitation always occurred at well-defined combinations of solvents and salts. At low concentration of monovalent salts, there was a linear correlation between the logarithm of the salt concentration and the inverse of the medium dielectric constant at a defined precipitation point. This is a strong indication that the stability of the solution depends almost exclusively on the balance of electrostatic forces. This behavior is compatible with the DLVO modeling of colloidal systems. When divalent salts were used, low concentrations of the counterion were sufficient to induce precipitation, due to a phenomenon called ionic condensation. Apparently, PRP precipitates when around 90% of its charges are neutralized, value that is similar to charge neutralization for DNA precipitation.

Authors+Show Affiliations

Laboratory of Process Development, Instituto Butantan, Av. Vital Brasil 1500, 05503-900 São Paulo, SP, Brazil; Department of Materials and Bioprocess Engineering, School of Chemical Engineering, University of Campinas (UNICAMP), Av. Albert Einstein 500, 13083-852 Campinas, SP, Brazil.Laboratory of Process Development, Instituto Butantan, Av. Vital Brasil 1500, 05503-900 São Paulo, SP, Brazil.Department of Materials and Bioprocess Engineering, School of Chemical Engineering, University of Campinas (UNICAMP), Av. Albert Einstein 500, 13083-852 Campinas, SP, Brazil. Electronic address: everson@feq.unicamp.br.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31419558

Citation

Simas, Rodrigo Gabriel, et al. "Study of the Polyribosyl-ribitol-phosphate Precipitation Mechanism By Salts and Organic Solvents." International Journal of Biological Macromolecules, vol. 140, 2019, pp. 102-108.
Simas RG, Takagi M, Miranda EA. Study of the polyribosyl-ribitol-phosphate precipitation mechanism by salts and organic solvents. Int J Biol Macromol. 2019;140:102-108.
Simas, R. G., Takagi, M., & Miranda, E. A. (2019). Study of the polyribosyl-ribitol-phosphate precipitation mechanism by salts and organic solvents. International Journal of Biological Macromolecules, 140, pp. 102-108. doi:10.1016/j.ijbiomac.2019.08.110.
Simas RG, Takagi M, Miranda EA. Study of the Polyribosyl-ribitol-phosphate Precipitation Mechanism By Salts and Organic Solvents. Int J Biol Macromol. 2019 Aug 13;140:102-108. PubMed PMID: 31419558.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Study of the polyribosyl-ribitol-phosphate precipitation mechanism by salts and organic solvents. AU - Simas,Rodrigo Gabriel, AU - Takagi,Mickie, AU - Miranda,Everson Alves, Y1 - 2019/08/13/ PY - 2019/01/10/received PY - 2019/07/15/revised PY - 2019/08/12/accepted PY - 2019/8/17/pubmed PY - 2019/8/17/medline PY - 2019/8/17/entrez KW - DLVO KW - Ethanol KW - Ion condensation KW - Polysaccharide KW - Precipitation KW - Solubility SP - 102 EP - 108 JF - International journal of biological macromolecules JO - Int. J. Biol. Macromol. VL - 140 N2 - Precipitation has been widely applied to purification and fractionation of biological macromolecules. Several physical-chemical factors contribute to the destabilization of those solutions, such as the nature of solvent employed, presence of salts, temperature, and concentration of the macromolecule. In the case of charged biopolymers, electrostatic forces are the major contributors to their stability in solution. However, the role of each variable and the exact mechanism of precipitation are not completely understood yet. The aim of this work was to study the precipitation of polyribosyl-ribitol-phosphate (PRP, a linear homogeneous anionic biopolymer) in presence of salts and non-solvents, in order to contribute to the elucidation of its precipitation mechanism. The solvents tested (acetone, ethanol, and isopropanol) presented distinct dielectric constants. The salts used (NH4Cl, NaCl, KCl, MgCl2, and CaCl2) differ by their cations. For each salt concentration, the solvent fraction that induces precipitation was identified and the dielectric constant of the bulk solution was calculated. Precipitation always occurred at well-defined combinations of solvents and salts. At low concentration of monovalent salts, there was a linear correlation between the logarithm of the salt concentration and the inverse of the medium dielectric constant at a defined precipitation point. This is a strong indication that the stability of the solution depends almost exclusively on the balance of electrostatic forces. This behavior is compatible with the DLVO modeling of colloidal systems. When divalent salts were used, low concentrations of the counterion were sufficient to induce precipitation, due to a phenomenon called ionic condensation. Apparently, PRP precipitates when around 90% of its charges are neutralized, value that is similar to charge neutralization for DNA precipitation. SN - 1879-0003 UR - https://www.unboundmedicine.com/medline/citation/31419558/Study_of_the_polyribosyl-ribitol-phosphate_precipitation_mechanism_by_salts_and_organic_solvents L2 - https://linkinghub.elsevier.com/retrieve/pii/S0141-8130(19)30248-X DB - PRIME DP - Unbound Medicine ER -