Conformational similarities between one-chain and two-chain tissue plasminogen activator (t-PA): implications to the activation mechanism on one-chain t-PA

The active sites of single-chain and two-chain tissue plasminogen activator (sct-PA, tct-PA) in solution were directly compared by the application of a series of nitroxide spin labels and fluorophores. These effective and sensitive probes are useful for monitoring small protein structure changes. Further analysis was carried out by the creation of molecular models of the protease domains of act-PA and tct-PA.