Sydney : Scientists have cracked the riddle of a clot-busting enzyme, potentially opening the way to more effective therapy for stroke, heart attack and cancer. Monash University researchers, led by James Whisstock and Paul Coughlin, have shown how the protein plasminogen is converted into plasmin, an enzyme that sweeps disease-causing clots and clears up damaged tissue. Clinicians currently use drugs called plasminogen activators to generate plasmin in treating heart attack and stroke patients, the journal Cell Reports said. Whisstock, professor of biochemistry and molecular biology at Monash, said scientists had been trying for nearly a century to understand how plasminogen is activated to plasmin, according to a Monash statement. "Now we can see the atomic details of the plasminogen, we can finally get a detailed picture of how the whole system works and how plasmin is produced," Whisstock said. "Plasminogen only yielded its secrets when exposed to the most focused and powerful X-rays the Synchrotron can currently produce - technology which has only become available in the past few years," said Tom Caradoc-Davies, from the Australian Synchrotron.