Separator isoelectric focusing for identification of alpha-1-antitrypsin (Pi M) subtypes

A modified analytical isoelectric focusing procedure on polyacrylamide gel slabs, offering increased resolving capacity, has been developed for identification of six subtypes of the most common alpha-1-antitrypsin (A-1-AT) phenotype, Pi M. Combination of commercial Ampholine and other ampoteric substances, so called separators, produces pH plateaus, determined by the properties of the the additatives. Equilibrium is reached after extended focusing time, whereby stabilization of A-1-AT through alkylation is advantagous. The significance of this high resolution method for applications of the Pi system in genetic studies, and the general relevance of the modifications for other analytical purposes are discussed. A new nomenclature recommendation is presented.