title: Separation of glutathione and its novel analogues and determination of their dissociation constants by capillary electrophoresis.
abstract: A CE protocol was developed to separate reduced glutathione and its four novel analogues UPF1 (Tyr(Me)-γ-Glu-Cys-Gly), UPF17 (Tyr(Me)-α-Glu-Cys-Gly), UPF50 (β-Ala-His-Tyr(Me)-γ-Glu-Cys-Gly), and UPF51 (β-Ala-His-Tyr(Me)-α-Glu-Cys-Gly), and their homo- and heterodimers by varying the ionic strength and/or pH of different BGEs. For the determination of dissociation constants (pK(a)) of the above-mentioned peptides the CE method was used. Effective electrophoretic mobilities of analytes were measured in the pH range 5.50-10.00 using optimized BGE with an ionic strength of 50 mM at 25°C. pK(a) values were calculated by fitting the experimental points to a suitable model with correlation coefficients higher than 0.99. The pK(a) values for imidazolyl, amino and thiol moieties of the analyzed peptides were in the range 5.94-6.29, 8.81-9.10, and 7.86-8.13, respectively.
authors.affiliation: Department of Chemistry, Tallinn University of Technology, Tallinn, Estonia. jana.kazarjan@gmail.com
authors.forename: Jana
authors.initials: J
authors.lastname: Kazarjan
authors.forename: Merike
authors.initials: M
authors.lastname: Vaher
authors.forename: Riina
authors.initials: R
authors.lastname: Mahlapuu
authors.forename: Mats
authors.initials: M
authors.lastname: Hansen
authors.forename: Ursel
authors.initials: U
authors.lastname: Soomets
authors.forename: Mihkel
authors.initials: M
authors.lastname: Kaljurand
mesh_terms: D002021:Buffers; D019075:Electrophoresis, Capillary / Q000379:methods*; D005978:Glutathione / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D010455:Peptides / Q000737:chemistry
chemical_list: D002021:Buffers; D010455:Peptides; D005978:Glutathione