[Isoelectric focusing in pH stable gradient of secretory immunoglobulin A of rabbits]

Rabbit secretory immunoglobulin A was focused in the ampholine system (pH 3-10, 4-6). The focusing of a 25-30 mg sample in the medium with a low ionic strength is accompanied by an intensive precipitation of immunoglobulin A at isopoints. The immunoglobulin A-ampholine complex is formed, protein molecules acquire a negative charge and migrate to the anode. The focusing of 10-15 mg protein in the medium with 2.10(-3) NaCl stabilizes the protein under study at isopoints. The immunoglobulin distributes in a zone of the isoelectric spectrum of pH 15-4.30 units with total pI 4.75.