Determination of acidity constants and ionic mobilities of polyprotic peptide hormones by CZE

0421961 - ÚOCHB 2014 RIV DE eng J - Článek v odborném periodiku
Šolínová, Veronika - Kašička, Václav
Determination of acidity constants and ionic mobilities of polyprotic peptide hormones by CZE.
Electrophoresis. Roč. 34, č. 18 (2013), s. 2655-2665. ISSN 0173-0835. E-ISSN 1522-2683
Grant CEP: GA ČR(CZ) GAP206/12/0453; GA ČR(CZ) GA13-17224S
Institucionální podpora: RVO:61388963
Klíčová slova: acid dissociation constant * gonadotropin-releasing hormones * ionization constant * peptides * pK(a)
Kód oboru RIV: CB - Analytická chemie, separace
Impakt faktor: 3.161, rok: 2013

CZE has been applied to determination of thermodynamic acidity constants (pK(a)) of ionogenic groups and actual ionic mobilities of polyprotic peptides-synthetic human and salmon gonadotropin-releasing hormones and their derivatives and fragments. First, the mixed acidity constants, pK(a,i)(mix), of ionogenic groups, and actual ionic mobilities, m(i), of gonadotropin-releasing hormone peptides were determined by nonlinear regression analysis of pH dependence of their effective electrophoretic mobilities. The effective mobilities were measured by CZE in a series of BGEs within a broad pH range (1.80-12.10), at constant ionic strength (25 mM) and reference temperature (25 degrees C). Second, the pK(a,i)(mix) values were recalculated to thermodynamic pK(a)s using the Debye-Huckel theory. Thermodynamic pK(a) of carboxyl groups was estimated to be in the range of 2.5-3.3 for C-terminal amino acids of the above peptides, and 5.2 for glutamic acid in the middle of peptide chain; pK(a) of imidazolyl group of histidine residues was in the range of 5.7-6.8, pK(a) of N-terminal amino group of the peptide with free N-terminus was equal to 6.2, pK(a) of phenol group of tyrosine residues was in the range of 9.8-10.8, and pK(a) of guanidinyl group or arginine residues reached values 11.1-11.3, depending on the position of the residues in the peptide and on the amino acid sequence of the peptide. Absolute values of actual ionic mobilities of peptides with charge number +/- 2 were in the range (14.6-18.6) x 10(-9) m(2)V(-1)s(-1), and ionic mobilities of peptides with charge number +/- 1 reached values (6.5-12.9) x 10(-9) m(2)V(-1)s(-1).
Trvalý link: http://hdl.handle.net/11104/0228271