scholarly journals Characterization of divalent cation interactions with AASTY nanodiscs

2021 ◽  
Author(s):  
Milena Timcenko ◽  
Anton A.A. Autzen ◽  
Henriette E. Autzen
Keyword(s):  
Lipid Bilayers ◽  
Divalent Cation ◽  
Divalent Cations ◽  
Size Exclusion ◽  
Great Promise ◽  
Amphiphilic Copolymers ◽  
Exclusion Chromatography ◽  
Soluble Aggregates

Amphiphilic copolymers show great promise in extracting membrane proteins directly from lipid bilayers into 'native nanodiscs'. However, many such copolymers are polyanionic and sensitive to divalent cations, limiting their applicability towards Ca2+ or Mg2+ dependent proteins. Here, we characterize the Ca2+ and Mg2+ sensitivity of poly(acrylic acid-co-styrene) (AASTY) copolymers using analytical UV and fluorescent size exclusion chromatography, enabling us to separate signals from nanodiscs, copolymers, and soluble aggregates. Determination of free Ca2+ ion concentrations in the presence of copolymer shows that divalent cation tolerance is dependent on not only specific characteristics of a copolymer, but also on its concentration. We see that high ionic strength protects against aggregation facilitated by divalent cations, which is prominent in nanodiscs isolated from excess free copolymer through dialysis. Overall, we conclude that the behavior of amphiphilic copolymers in the presence of divalent cations is more complex than precipitation beyond a specific cation concentration.

scholarly journals Methods for preliminary determination of pemetrexed in macromolecular drug-carrier systems

2016 ◽  
Vol 66 (1) ◽  
pp. 147-153 ◽  
Author(s):  
Jarosław Ciekot ◽  
Tomasz Marek Goszczyński ◽  
Janusz Boratyński
Keyword(s):  
Drug Carrier ◽  
Size Exclusion ◽  
Small Cell Lung ◽  
Absorption Spectrophotometry ◽  
Limit Of Quantitation ◽  
Exclusion Chromatography ◽  
Carrier Systems ◽  
Drug Carrier Systems

AbstractPemetrexed (PMX) is an antifolate drug utilized in the treatment of non-small cell lung cancer. For studies of potential macromolecular carriers for PMX, fast and precise methods were developed to determine the bound and free drug contained in investigated conjugate preparations. The analysis of the total amount of PMX in conjugates was based on absorption spectrophotometry. The linearity was found in the range of 4.697–46.97 μmol L−1PMX. The limit of quantitation was 1.070 μmol L−1. The method for the analysis of unbound PMX was based on size-exclusion chromatography and detection at 225 nm. This method shows linear range of 2.230–223.0 μmol L−1.LOQwas 0.539 μmol L−1. The proposed methods can be used both for the characterization of the polysaccharide based conjugates of PMX and for the determination of conjugate drug release profiles.

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