Affinity capillary electrophoresis employed for determination of stability constants of antamanide complexes with univalent and divalent cations in methanol

Abstract

Affinity capillary electrophoresis (ACE) and pressure‐assisted ACE were employed to study the noncovalent molecular interactions of antamanide (AA), cyclic decapeptide from the deadly poisonous fungus Amanita phalloides, with univalent (Li+, Na+, K+, and NH4+) and divalent (Mg2+ and Ca2+) cations in methanol. The strength of these interactions was quantified by the apparent stability constants of the appropriate AA‐cation complexes. The stability constants were calculated using the nonlinear regression analysis of the dependence of the effective electrophoretic mobility of AA on the concentration of the above ions in the BGE (methanolic solution of 20 mM chloroacetic acid, 10 mM Tris, pHMeOH 7.8, containing 0–50 mM concentrations of the above ions added in the form of chlorides). Prior to stability constant calculation, the AA effective mobilities measured at actual temperature inside the capillary and at variable ionic strength of the BGEs were corrected to the values corresponding to the reference temperature of 25°C and to the constant ionic strength of 10 mM. From the above ions, sodium cation interacted with AA moderately strong with the stability constant 362 ± 16 L/mol. K+, Mg2+, and Ca2+ cations formed with AA weak complexes with stability constants in the range 37–31 L/mol decreasing in the order K+ > Ca2+ > Mg2+. No interactions were observed between AA and small Li+ and large NH4+ cations.

Recent developments in capillary and microchip electroseparations of peptides (2019–mid 2021)

“…Nonaqueous CE (NACE) [102] in pure organic solvents, such as ACN, MeOH, and isopropyl alcohol (IPA), or CZE in mixed hydro‐organic solvents are suitable for analysis of water‐insoluble or poorly soluble peptides and peptidomimetics and/or for modification of selectivity of CE separations of peptides exhibiting identical or very close mobilities in aqueous BGEs. NACE using MeOH solvent and BGE composed of 20 mM chloroacetic acid and 10 mM Tris, with pH MeOH 7.8 (defined on the basis of the known p K a value of chloroacetic acid in MeOH) was employed for the study of the interaction of the cyclic peptide antamanide with selected metal and ammonium cations [103].…”

Antamanide Analogs as Potential Inhibitors of Tyrosinase

“…In order to improve the hydrophilicity of this peptide, the Phe residue at either the six or nine positions was replaced with a Gly residue. Previous studies showed that the substitution of Gly for Phe at these positions did not induce loss of the characteristic ion binding properties, maintaining the ions selectivity determined for antamanide (Ca > Na >> K) [ 21 ], while their cytotoxic activity on B16F10 metastatic cells is reduced compared to the parent peptide antamanide. Indeed, only the AG9 peptide showed a comparable activity after 48 h of treatment, while both AG6 and AOG9 resulted in being non-cytotoxic [ 14 ].…”

Studying molecular interactions via capillary electrophoresis and microscale thermophoresis: A review

“…In 2019, both ms‐ACE and PA‐ms‐ACE methods were employed to study the noncovalent molecular interactions of antamanide (AA), cyclic decapeptide from the deadly poisonous fungus Amanita phalloides, with univalent (Li + , Na + , K + , and NH 4 + ) and divalent (Mg 2+ and Ca 2+ ) cations in methanol [104], whereas in 2020, PA‐ms‐ACE with ICP‐MS detection was used for confirmation of interaction of carboxylated core–shell magnetic nanoparticles with polymyxin B [128].…”