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Enzyme 42 is an enzyme found in almost every life form on Planet 4546B but is only produced by the Sea Emperor Leviathan species as a digestive enzyme. It is the only known cure for the Kharaa Bacterium. The Precursors were investigating how to produce a cure using Enzyme 42. The Sea Emperor Leviathan trained the Peepers, to use the Alien Vents, carry small amounts of the enzyme, having collected it from the captive Sea Emperor Leviathan, distributing it throughout the planet.

The Sea Emperor Leviathan occasionally releases Enzyme 42 as a cloud whilst it swims around the aquarium, while the Babies release it as a solid ball of concentrated Enzyme 42. This may reflect the unstable nature of the captive's Enzyme. The solid ball of Enzyme 42 cannot be picked up, and the player may only put his hand in the ball to cure himself. If an infected creature touches the ball, it will no longer look infected. The solid ball is also not scannable, as may be that not much is known to the PDA, therefore there is no databank entry.


The Sea Emperor Leviathan species produces the enzyme naturally, which resulted the Precursors capturing an adult and its five eggs and putting it in the Primary Containment Facility. However, due to the captive's age, the Enzyme 42 it produced was unstable and could only temporarily revert the infection. However, the Precursors then deduced that the unborn Sea Emperor Leviathans would likely be a better source, although they could not figure how to hatch the eggs themselves.

After Ryley Robinson hatches the infant Sea Emperor Leviathans, he interacts with a concentrated ball of Enzyme 42, and is thus cured. The Sea Emperor Leviathan Babies then migrate through the Alien Arch and become juveniles, where they spread the enzyme throughout Planet 4546B.

Data Bank Entries

According to translated data logs, an indigenous leviathan species was found to produce a unique substance referred to as 'Enzyme 42', which inhibited the symptoms of the kharaa bacterial infection in other indigenous organisms. The specimen was captured and contained in a purpose-built habitat for further study.

The alien researchers went to great lengths to provide for the lifeform's environmental needs, including the import of interdependent flora and fauna via an onsite warpgate, however its health quickly deteriorated.

When quarantine was imposed all warp gates and forcefields were sealed. All attempts to develop the enzyme into a vaccine had been unsuccessful.

Analysis of the enzyme-production organs in the sea emperor species indicates that it may be possible to permanently purge the alien bacteria from a human system with a sufficiently stable enzyme sample. Unfortunately the emperor specimen contained within the alien facility is in poor health and unlikely to produce enzyme with the necessary strength. A juvenile of the species would provide a higher chance of success.

Scans indicate this infected organism has recently come into contact with a unique enzyme which has counteracted the most debilitating symptoms of its infection.

- Skin blistering has rapidly receded and been replaced with healthy tissue
- Altered genetic material has been replaced with original DNA from remaining healthy cells
- Behavior normal
- The bacteria is still present in the bloodstream, but is currently dormant

Assessment: Investigate enzyme origin



  • The name may be a reference to Douglas Adams' The Hitchhiker's Guide to the Galaxy, where 42 is the answer to the Ultimate Question of Life, the Universe, and Everything. This could be due to the fact that Enzyme 42 is the cure to a fatal illness, the Kharaa Bacterium, thus making it the answer to life.
  • In Subnautica: Below Zero, it was revealed (although not explicitely confirmed) that the Sea Dragon Leviathan might have possibly also produced Enzyme 42. However, it is likely that any creature that tried to collect eggs from the Sea Dragon Leviathan died trying.