WASHINGTON, March 20 (Xinhua) -- Researchers have reported the X-ray crystallography structure of the SARS-CoV-2 main protease -- one of the best characterized drug targets among coronaviruses, according to a new study published Friday in the journal Science.

The research is part of the continued efforts to respond to the COVID-19 pandemic caused by SARS-CoV-2 virus. Insights from the study could drive design of better inhibitors for the novel coronavirus, a step toward urgently needed therapies to fight the global pandemic.

For viruses like HIV, effective drugs block the main virus protease -- an enzyme that processes proteins critical to virus development.

The research, led by Linlin Zhang, a researcher at the University of Lubeck in Germany, has reported the crystal structure of the main protease of SARS-CoV-2 at 1.75 angstrom resolution.

Based on studying the structure of the main protease, the researchers optimized inhibitors for existing coronaviruses to develop compound 13b, a potent blocker of the SARS-CoV-2 main protease.

They reported that 13b has features that improve over existing inhibitors, including an extended half-life in blood plasma. They also reported a high-resolution structure of 13b bound to the protease.

The researchers tested a leading inhibitor compound in mice, finding that inhalation was well tolerated, and mice did not show any adverse effects.

Their results suggest that direct administration of the compound to the lungs may be possible and provide a framework for the development of drugs to combat the novel coronavirus, according to the study.