Two forms of alpha 2-antiplasmin: differences in KAV and isoelectric point

The plasminogen-binding (PB-AP) and the non-plasminogen-binding (NPB-AP) forms of alpha 2-antiplasmin were assayed by a modified rocket electroimmunoassay technique using an intermediary gel containing kringles 1-3 from plasminogen. Gel chromatography of normal human plasma (HNP) showed differences in KAV between PB-AP and NPB-AP. PB-AP had a KAV of 0.33 and NPB-AP a KAV of 0.39. Isoelectric focusing of HNP showed pI differences between PB-AP and NPB-AP. PB-AP was heterogeneous, with a main peak at pI = 4.69 and a minor peak at pI = 4.92, while NPB-AP had only one peak, at pI = 4.59.