title: Mass distribution, polydispersity and focusing properties of carrier ampholytes for IEF II: pH 4-6 intervals.
abstract: For studying the M(r) distribution and number of species in narrow-range (2 pH-unit wide, in the nominal pI 4-6 interval) carrier ampholytes from four commercial sources (Bio-Lyte, Servalyt, Ampholine and Pharmalyte), a 2-D technique was adopted consisting of a focusing step in a liquid phase (Rotofor, yielding 20 fractions) followed by orthogonal CE in both, acidic and basic buffers. As a final step, every other fraction was analyzed by CE-MS. The findings: Ampholine contains 80 different M(r) compounds, in the M(r) interval 203 to 893 Da, for a total of 325 isoforms. Bio-Lyte consists of 66 different M(r) species, in the M(r) range 388 to 835 Da, for a total of 436 isoforms. Servalyt is made of 199 different M(r) compounds, in the M(r) interval 204 to 907 Da, for a total of 1302 isoforms. Pharmalyte pH 4-6.5, comprises 217 amphoteres, in the M(r) range 150 to 1179 Da, for a total of 812 isoforms. Pharmalyte appears to be the best brand, with the vast majority of species focusing sharply at their pI position and <5% "poor" species, distributed along the entire pH gradient, denoting an extremely shallow pH/mobility curve across the pI value.
authors.affiliation: Politecnico di Milano, Department of Chemistry, Materials and Engineering Chemistry Giulio Natta, Milano, Italy.
authors.forename: Carolina
authors.initials: C
authors.lastname: Simó
authors.forename: Martha Elena
authors.initials: ME
authors.lastname: Mendieta
authors.forename: Paolo
authors.initials: P
authors.lastname: Antonioli
authors.forename: Roberto
authors.initials: R
authors.lastname: Sebastiano
authors.forename: Attilio
authors.initials: A
authors.lastname: Citterio
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cifuentes
authors.forename: Gabriel
authors.initials: G
authors.lastname: Peltre
authors.forename: Pier Giorgio
authors.initials: PG
authors.lastname: Righetti
mesh_terms: D000665:Ampholyte Mixtures / Q000032:analysis* / Q000592:standards*; D002021:Buffers; D019075:Electrophoresis, Capillary; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D008970:Molecular Weight
chemical_list: D000665:Ampholyte Mixtures; D002021:Buffers