The assay of prekallikrein activator in human blood products

An assay for the determination of prekallikrein activator (PKA) in human blood products is described. Kallikrein released from a prekallikrein substrate preparation by PKA in the sample is determined using the synthetic substrate S-2302 (H-D-Pro-Phe-Arg-pNA). The PKA content of the sample is quantitated by interpolation from a standard line obtained using a reference preparation of plasma protein fraction (PPF). Endogenous kallikrein is estimated and an adjustment made for its contribution to the apparent PKA content of the sample. The results of determinations on a number of PPF, immunoglobulin and coagulation factor preparations are presented and discussed.