PHYSICAL CHARACTERIZATION OF RECOMBINANT TISSUE-PLASMINOGEN ACTIVATOR

Electron microscopic and physical-chemical properties of one- and two-chain tissue plasminogen activator (t-PA) were studied. The molecular weight of one-chain t-PA obtained by both sedimentation equilibrium and SDS-PAGE was estimated to be about 65000, while both chains in the reduced two-chain form were in the range of 35000-40000. Sedimentation coefficients were identical for both forms of t-PA (S20,w0 = 4.12). The two forms of t-PA were indistinguishable by electron microscopic analysis, which confirmed the sedimentation results, and showed that they were ellipsoidal end relatively compact. The major and minor axes were approx. 13 nm and approx. 10 nm and f/f0 was 1.36. The individual domains of t-PA are relatively small and are folded within the molecule, so that the overall appearance is globular.