| Molecular weight (d) | Activity | |
| Plasminogen | 88,000 (single chain) | Proenzyme form of fibrinolytic enzyme |
| Plasmin | 88,000 (two chain) | Active fibrinolytic enzyme |
| TPA | 70,000 (one/two chain) | Enzyme present in tissues that coverts plasminogen to plasmin |
| UPA | 54,000 (two chain) | Plasminogen activator (different from tPA) |
| α2PI | 70,000 (single chain) | Specific fast-acting inhibitor in plasma |
| PAI-1 | 40,000 (single chain) | Fast-acting inhibitor of tPA (and UPA) secreted by endothelial cells) |
