The Role of THCA Synthase in Cannabis

The world of cannabis research is complex and full of discovery. A major leap forward in this field came when a group of scientists successfully cloned a specific gene that encodes for an enzyme called THCA synthase. This was reported in a significant study published in the Journal of Biological Chemistry.

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The team conducted their research on Cannabis sativa, a common variety of cannabis. Their focus was on the rapidly growing leaves of these plants, where they made their remarkable discovery.

They found that the THCA synthase gene is a specific part of the plant's DNA - an instruction manual of 1635 units long, which holds the directions to create a chain of 545 parts, or amino acids.

Among these amino acids, the first 28 constitute what's known as a signal peptide. This segment is like the GPS for the enzyme, guiding it to the correct location within the cell where it can perform its functions. Without this guidance system, the enzyme could lose its way and not end up where it's needed.

Once the enzyme has reached its destination and is ready to do its job, it forms into what is known as a mature polypeptide. This is a chain of 517 amino acids with a molecular weight of 58,597 Da, a scientific unit used to measure the mass of molecules.

To put it in simpler terms, scientists found a specific 'blueprint' within the DNA of cannabis plants that is responsible for producing an important worker enzyme, THCA synthase. This enzyme has a built-in address system that ensures it gets to the right place within the cell to do its job.

THCA Synthase and Berberine Bridge Enzyme: A Surprising Connection

As the researchers delved deeper into the mysteries of THCA synthase, they made another fascinating discovery. When they examined the sequence of amino acids that make up THCA synthase, they found it looked a lot like another enzyme from a completely different plant, the Eschscholtzia californica. This enzyme, called berberine bridge enzyme, plays an important role in creating a group of chemicals known as alkaloids.

This resemblance suggests that there could be an evolutionary link between the ways cannabinoids, like those in cannabis, and alkaloids are made in plants. This is an intriguing prospect that could open up whole new areas of study for understanding how plants create these complex chemicals.

The scientists found that the 'recipe' for making the cannabis enzyme THCA synthase looks a lot like the 'recipe' for an enzyme in a different plant. 

This could mean that these plants might use similar methods to make their unique chemicals. This discovery not only deepens our understanding of how plants work, but also opens up exciting possibilities for future research.

The Functionality Test: Confirming the Role of THCA Synthase

After the groundbreaking discovery and cloning of the THCA synthase gene, it was crucial for the scientists to confirm its role. They needed to check that this gene really does what they believed it does - create THCA synthase.

To test this, the researchers introduced the cloned gene into a completely different plant - tobacco. The scientists worked with a special kind of genetically altered tobacco that produces what are called 'hairy roots.' They fed these roots cannabigerolic acid, the raw material or 'starter ingredient' that THCA synthase uses to make THCA. 

If the gene worked as expected, it would take this starter ingredient and transform it into THCA. The results were a success! 

The tobacco roots produced THCA, confirming that the gene did indeed create an active THCA synthase. This was solid proof that the cloned gene was functional and correctly coded for THCA synthase.

In everyday language, think of the gene as a recipe for a particular dish, say a cake. The scientists found this recipe (gene) in a cannabis plant and believed it told them how to make a specific kind of cake (THCA synthase). 

To be sure, they used the recipe in a different kitchen (tobacco plant). When they provided the right ingredients (cannabigerolic acid), they ended up with the cake they expected (THCA). 

This was proof that the recipe was indeed for that specific cake.

The Overexpression and Intricacies of THCA Synthase

Following the successful cloning and functionality test of the THCA synthase gene, the researchers proceeded to the next stage of their study. They wanted to produce a lot of the THCA synthase enzyme in a lab setting. This process, known as overexpression, was carried out using a system that involves a baculovirus and insect cells.

Once they had a large quantity of THCA synthase, the scientists discovered something interesting. The enzyme contained a special helper molecule called an FAD cofactor, firmly attached to it. This molecule is essential for the enzyme to carry out its job.

To understand the importance of this helper molecule, the researchers made a small change in the enzyme. They altered a single amino acid, changing it from His-114 to Ala-114. 

This mutation resulted in the enzyme no longer being able to bind the FAD cofactor, which in turn prevented the enzyme from functioning properly. This clearly demonstrated that the THCA synthase reaction is dependent on the FAD cofactor.

To make this easier to understand, imagine the THCA synthase as a machine in a factory that needs a specific key to operate. The FAD cofactor is that key. If the key slot (the His-114 amino acid) is altered, the key (FAD cofactor) can't fit, and the machine (THCA synthase) can't work. This discovery highlights the essential role the FAD cofactor plays in the function of THCA synthase.

The Impact: A Landmark Achievement in Cannabinoid Research

The conclusion of this study signals a tremendous breakthrough in cannabinoid research. For the first time ever, we have a detailed molecular report about an enzyme—THCA synthase—that plays a key role in the formation of cannabinoids. These findings go a long way in enriching our understanding of how these unique compounds are produced within the cannabis plant.

But the implications of the study stretch far beyond just understanding the process. It's akin to having learned the secrets of a master chef's recipe. Now that we understand the 'cooking' process, we can experiment, tweak, and potentially enhance the 'dish'—that is, the cannabis plant. This knowledge could potentially be used to manipulate the levels of cannabinoids in cannabis, which is exciting for both medicinal and recreational applications of the plant.

Think of it as finally having the secret recipe for grandma's special soup. Not only can we appreciate the soup more now that we know what goes into it, but we also have the chance to experiment with the ingredients. We could potentially make the soup spicier, creamier, or saltier, depending on what we desire. In the same way, this study gives us the tools to potentially shape the future of cannabis to better suit our needs.


Sirikantaramas, S., Morimoto, S., Shoyama, Y., Ishikawa, Y., Wada, Y., Shoyama, Y., & Taura, F. (2004). The gene controlling marijuana psychoactivity: molecular cloning and heterologous expression of Delta1-tetrahydrocannabinolic acid synthase from Cannabis sativa L. Journal of Biological Chemistry, 279(38), 39767-74. doi: 10.1074/jbc.M403693200. Click here to read the study.

Author | Chris McDonald

With two decades of expertise, Chris leads Happy Hydro in redefining sustainable gardening and delights in backpacking adventures, mind-expanding journeys, and creating memories with his loved ones.

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