"Identify the molecule" league #37. Prize: knowledge + 5 Hive + 100 STEM + 100 CCC + 100 PAL + 200 TMN

This contest is an attempt to promote scientific knowledge among community in a fun and interesting way with the help of molecules.
Some people like to travel around the world and tell others stories about what happens outside of our organisms/cells in other countries.
And with “Identify the molecule” contest you can try to travel inside our own organism/cells and cells of the organisms around us.

Important
In order to get TMN, you’ll need to have NEO-wallet and provide me your public NEO-address.
If you don’t have it yet, don’t worry, I published a post on how/where to get it (O3 wallet).
Note that NEO-addresses provided by exchanges will not work in this case (+ it's safer NOT to keep your funds on exchanges). It's highly recommended to get O3 wallet.

For more information about this contest and its rules (especially if you're new to it) read

"Identify the molecule" contest. Upgrade (the league, additional bonuses and more)

and

"Identify the molecule" league #30. Prize: knowledge + 5 Hive + 100 STEM + 100 CCC + 100 PAL + 200 TMN

If there’re no winners on any stage, the bonuses will be distributed equally among all users who provided any guesses for molecules.

All participants with guesses for molecules (not just the winners) are going to be rewarded with 20 STEM + 100 CCC + 100 PAL.

Riddle

Today's riddle is about the enzyme essential for nitrogen metabolism (takes part in ammonia detoxification).
The enzyme can be found as in prokaryotes, as in eukaryotes.
In humans it can be found mostly in brain tissues (astrocytes)
(some studies show the link between activity level of the enzyme and neurological disorders) and hepatocytes, and is represented as homodecamer (10 sub-units organized in 2 pentameric rings) (and the enzyme presented on the image below is from procaryotes (12 sub-units)). Two adjacent sub-units form an active site (which gives 10 catalytic sites in total for people and 12 for procaryotes).

(Surface representation. The image was created by me with the help of PyMol - open source tool for molecular visualization/exploration. PDB-file was obtained from PDB)

Rules

This contest lasts for 6 days.

Leave your guess (1 guess only (not 2 or 3+)) in the comments section of the post.

Don’t edit your comment/Don't delete or add new comments with the answers and don’t provide any evidence that your answer is correct.

The first user with correct answer is the winner.

Some of the clues have already been provided in the post.

Additional clues will be given Wednesday (20:00 ± 15 minutes UTC) (I’ll update this post).

The reason is that some people might need less information to make conclusions that the others.

Additional clues will be added at the end of the "Riddle" section before the "Rules" section with "Edited" label.

The winner will be announced on Friday, September 18, 2020, 20:00 ± 15 minutes UTC in the comments section of the next post. Plus I’ll publish a detailed review of the riddle after a while.

I’ll transfer the tokens (STEM + Hive + TMN + CCC + PAL) (if the winner provides me his/her NEO-address) to the winner on that day and add the transaction ID in the comments section.

I’m planning to run this contest every week.
So, you should expect to see the 2nd week’s riddle for September on Saturday, September 19, 2020, 20:00 ± 15 minutes UTC.

References

I’ll add all the references for this post later, because most of them contain the name of the molecule.
That would be a spoiler.
I’ll add them after a while.

Important

This contest is the work in progress.
A lot can be changed in the future.
Any recommendations/suggestions are very welcome.
If you have any questions, feel free to ask them in the comments section.

All images (without the license specified) are used under the doctrine known in USA as "Fair Use" (similar doctrines are used in other countries). For more information visit the US Gov website