title: Stable storage conditions of Immobiline chemicals for isoelectric focusing.
abstract: Most of the problems connected with the use of the Immobiline chemicals (a set of six, non-amphoteric, acrylamido buffers having pK values in the pH 3.5-9.5 interval) can be attributed to the alkaline species (with pK values 6.2, 7.0, 8.5 and 9.3). These compounds, to varying degrees are subjected to two degradation pathways: (a) hydrolysis of the amido bond, producing free acrylic acid and a diamine, the latter unable to be incorporated into the polyacrylamide matrix; (b) spontaneous auto-polymerization, producing a number of oligomers up to n-mers, able to aggregate and precipitate large proteins. Storage of their water solutions as frozen aliquots, a method widely employed, only partially alleviates the problem. Addition of trace-amounts of inhibitors, as lately adopted by the manufacturer, could only reduce the problem of auto-polymerization, but not block the hydrolysis of the amido bond. A new solution has been found, which abolishes both phenomena: storage in n-propanol. As demonstrated by gas chromatography, HPLC analyses and two-dimensional separations of complex samples, storage in organic solvent completely abolishes both hydrolysis and auto-polymerization and allows production of highly reproducible focusing patterns.
authors.affiliation: Pharmacia LKB Biotechnology AB, Bromma, Sweden.
authors.forename: B M
authors.initials: BM
authors.lastname: Gåveby
authors.forename: P
authors.initials: P
authors.lastname: Pettersson
authors.forename: J
authors.initials: J
authors.lastname: Andrasko
authors.forename: L
authors.initials: L
authors.lastname: Ineva-Flygare
authors.forename: U
authors.initials: U
authors.lastname: Johannesson
authors.forename: A
authors.initials: A
authors.lastname: Görg
authors.forename: W
authors.initials: W
authors.lastname: Postel
authors.forename: A
authors.initials: A
authors.lastname: Domscheit
authors.forename: P L
authors.initials: PL
authors.lastname: Mauri
authors.forename: P
authors.initials: P
authors.lastname: Pietta
mesh_terms: D000433:1-Propanol; D002021:Buffers; D002849:Chromatography, Gas; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D004356:Drug Storage; D006868:Hydrolysis; D007525:Isoelectric Focusing; D011108:Polymers
chemical_list: D002021:Buffers; D011108:Polymers; D000433:1-Propanol