Proteolytic Enzymes for COVID-19 Studied in 3D for the First Time in Thailand by Chula Biochemists

Bangkok, Thailand – A team of biochemists from Chulalongkorn University became the first researchers in Thailand to study proteolytic enzymes for the Covid–19 virus at a molecular level in 3D, possibly leading to the development of Covid–19 treatments.

“To combat the outbreak, we have applied biochemistry to various applications that counter Covid- 19, from hand sanitizing gels to enzymes used in Covid-19 test kits. Most recently, we became the first and only institution in Thailand to study proteolytic enzymes for the Covid–19 virus at the molecular level, in 3D, which may potentially lead to Covid-19 antiviral drugs,” said Dr. Kittikhun Wanganont and Asst. Prof. Dr. Thanyada Rungrojmongkol from the Department of Biochemistry, Faculty of Science, Chulalongkorn University.

Assistant. Prof. Dr. Thanyada Rungrojmongkol. Photo: Chulalongkorn University.

As the world races to find a stop for the Covid-19 pandemic, scientists and medical professionals have been focused on coming up with vaccinations to create antibodies that can block the virus from infecting the cells. However, vaccines are not the only solution to stop Covid-19 and other viruses. “We may have heard of the use of HIV/AIDs antiviral drugs to combat Covid-19 through the inhibition of a certain enzyme. Similar to the HIV/AIDS virus, Covid-19 creates a long string of multi- proteins, which need proteolytic enzymes in order to break into smaller pieces to perform different functions. Around the world, scientists believe that this is a possible springboard for new drugs”, explained Dr. Kittikhun.

Covid–19 study. Image: Chulalongkorn University.

The SARS, MERS, and the current Covid-19 viral outbreaks have shifted researchers around the world to study viral proteases. In late January 2020, China was the first country to study proteases on a molecular scale. Following suit were scientists from the United Kingdom, Germany, the United States, and Thailand by the Department of Biochemistry, Faculty of Science, Chulalongkorn University.

Image shows the prevention of proteolysis by the Covid–19 protease inhibitors in the Chinese study (red). Image: Chulalongkorn University.

“We populate chemically synthesized protease genes in bacteria, allowing us to produce a large quantity of protease. Then, they can be tested on various drugs for bonding probability, not only via computer simulation but also in laboratory tests. In so doing, we can shorten the timeframe of finding Covid-19 medicine from the usual span of ten years.”

“About 60 drugs have passed our screen tests, some of which are still pending order from abroad, and some are duplicates of the ones being studied in China. From our studies, three or four drugs have potential. Also, we have tested over 50 herbs. The way we work is, we pair the already- approved drugs with the protease structures to discover which active ingredients in the drugs can inhibit the enzymes. Our studies are then used for continued research in laboratory testing.”

Another achievement for the Department of Biochemistry is protein crystallization. Similar to the crystallization of salt and sugar, water evaporates from the protein, reaches the supersaturated state, then crystallizes. Researchers can then collect the minuscule pieces of crystals, invisible to the naked eye, using a needle. The crystals are exposed to concentrated X-ray microbeams using a synchrotron in Illinois, U.S.A. This allows researchers to view diffraction patterns of the atoms and molecules.

SARS–CoV–2 main protease crystals under polarized light. Image: Chulalongkorn University.

With the Department of Biochemistry’s capability to synthesize large quantities of protease, combined with the ability to analyze protein structures at the molecular level, we have the capability to test various Thai herbs with the protein micro crystallography, using synchrotron radiation. At present, the Department of Chemistry and the Faculty of Medicine are cooperating on chemical testing of Thai herbs.

“A common question has been whether or not green chiretta (Kariyat/Fah Talai Jone/Andrographis paniculate) or the HIV/AIDS antiviral drugs can be used to treat Covid-19; and how much should be administered. What the Biochemistry Department has managed to do is to find scientific proofs in this area to answer Thai researchers’ questions. With our upstream capacity of synthesizing our own proteases, we can test Thai herbs with the protein micro crystallography process using synchrotron radiation. We can study the herbs’ ability to inhibit the virus, observe it in 3D on a computer, an eventually develop a new generation of drugs,” continued Prof. Dr. Thanyada.

Electron density map. Image: Chulalongkorn University.

Dr. Kittikhun further reiterated that, in combatting the rapidly-mutating Covid-19 virus, all measures, including vaccines, test kits, and treatments, need to be developed concurrently. A number of medications are needed to treat the symptoms, and the mitigation measures need to be comprehensive. To put one’s hope on only one of these things is risky.

“People may say that work such as this is upstream research which does not yield immediate results. However, research like this does not cost a lot of money. At the moment, we have the 5 testing capability and whether or not it would be applied to the actual virus, used in medical research, and/or further developed, depends on funding availability and the research community’s interest in further development.”

Diffraction pattern. Image: Chulalongkorn University.

“In mid-September, the U.S. pharmaceutical company, Pfizer, announced that it had begun trials on its protease inhibitors antiviral drugs. Our drug research is still very much behind overseas. If there is a further outbreak in Thailand, we need to be more prepared.” Dr. Kittikhun concluded.

By Chulalongkorn University