1. A pharmaceutical composition comprising a metalloproteinase fibrinolytic agent selected from the group consisting of fibrolase and novel acting thrombolytic (NAT), a zinc stabilizer and, optionally, a bulking agent, in a pharmaceutically-acceptable buffer. 2. The pharmaceutical composition of claim 1 wherein the zinc stabilizer is a water soluble zinc salt selected from the group consisting of zinc sulfate, zinc acetate and zinc chloride. 3. The pharmaceutical composition of claim 1 wherein the buffer is citric acid or a water soluble citric acid salt. 4. The pharmaceutical composition of claim 1 wherein the bulking agent is mannitol. 5. The pharmaceutical composition of claim 1 which has a pH in the range of about 6.5 to about 8.5. 6. The pharmaceutical composition of claim 1 which is in the form of a frozen liquid. 7. The pharmaceutical composition of claim 6 which optionally contains a water soluble calcium salt. 8. The pharmaceutical composition of claim 7 in which the water soluble calcium salt is selected from the group consisting of calcium acetate, calcium sulfate and calcium chloride. 9. The pharmaceutical composition of claim 1 which is lyophilized. 10. The pharmaceutical composition of claim 1 wherein the metalloproteinase has the amino acid sequence of SEQ ID NO: 1. 11. An aqueous pharmaceutical composition comprising about 0.1 to about 50 mg/ml of a metalloproteinase fibrinolytic agent selected from the group consisting of fibrolase and novel acting thrombolytic (NAT), about 0.08 to about 0.12 mM of zinc sulfate, about 0.008 mM to about 0.012 mM of calcium acetate, and about 95 to 110 mM of citric acid or sodium citrate, with the pH of said composition being about 7.4. 12. A pharmaceutical composition according to claim 11, comprising 10 mg/ml of the metalloproteinase in an aqueous solution comprising 100 mM of citric acid, 0.01 mM calcium acetate and 0.1 mM zinc sulfate. 13. An aqueous pharmaceutical composition comprising about 0.1 to about 50 mg/ml of a metalloproteinase fibrinolytic agent selected from the group consisting of fibrolase and novel acting thrombolytic (NAT), about 0.08 to about 0.12 mM of zinc acetate, about 18 to about 22 mM of citric acid or sodium citrate, about 0.02 to about 0.06 mM of Tris, about 3 to about 6 percent (w/v) of mannitol, and about 0.008 to about 0.012 percent (w/v) of Tween 80, with the pH of said composition being about 8.0. 14. An aqueous pharmaceutical composition suitable for lyophilization, comprising about 0.1 to about 50 mg/ml of a metalloproteinase fibrinolytic agent selected from the group consisting of fibrolase and novel acting thrombolytic (NAT), about 0.08 to about 0.12 mM of zinc sulfate, about 18 to about 22 mM of citric acid or sodium citrate, about 3 to about 6 mM of Tris, about 3 to about 6 percent (w/v) of mannitol, and about 0.008 to about 0.012 percent (w/v) of Tween 80, and optionally about 0.1 to about 0.5 percent (w/v) of sucrose, with the pH of said composition being about 8.0. 15. A pharmaceutical composition according to claim 14, comprising 12 mg/ml of the metalloproteinase, 5 mM of Tris, 20 mM of citric acid, 5 percent (w/v) of mannitol, 0.5 percent (w/v) of sucrose, 0.01 percent (w/v) of Tween 80, and 0.1 mM of zinc sulfate, with the pH of said composition being about 8.0. 16. A method for preparing a lyophilized composition, comprising the steps of: (a) forming a mixture of a metalloproteinase fibrinolytic agent selected from the group consisting of fibrolase and novel acting thrombolytic (NAT), a zinc salt, a bulking agent, a stabilizing disaccharide and a surfactant in a buffer, and (b) lyophilizing the mixture from step (a). 17. The method of claim 16, in which the pH of said composition is adjusted to between about 7.8 and about 8.2 prior to lyophilization. 18. The method of claim 16, comprising the steps of: (a) adjusting the pH of a solution containing the zinc salt, bulking agent, and stabilizing disaccharide to a Ph between 7.6 and 8.2, (b) buffer exchanging solution containing the metalloproteinase into the solution of step (a), and then adding an effective amount of the surfactant, and (c) lyophilizing the mixture of step (b). 19. A lyophilized pharmaceutical composition prepared by the method of claim 18. 20. A method comprising the steps of reconstituting the aqueous pharmaceutical composition of claim 1 which has been lyophilized and administering the reconstituted composition to a patient in need of blood clot lysis. 21. A kit for preparing an aqueous pharmaceutical composition comprising a first container having a lyophilized composition of a metalloproteinase fibrinolytic agent selected from the group consisting of fibrolase and novel acting thrombolytic (NAT) and a second container having a physiologically acceptable solvent for the lyophilized composition.