What’s in a name? Restriction Enzymes Edition

A rose by any other name would smell as sweet. Would a restriction enzyme by another name cut as well? Probably. However, restriction enzymes also have a standardized naming system that ensures each enzyme’s name is unique. That’s good news as there are over 3,000 restriction enzymes currently used by scientists.

Helixitta, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0&gt;, via Wikimedia Commons

Restriction enzymes are endonucleases that catalyze the cleavage of phosphodiester bonds within both DNA strands. The sites of cleavage occur in or near very specific palindromic sequences of bases called recognition sites, which are generally 4 to 8 base pairs long. In bacteria as well as some archaea, these enzymes are an essential defense against viruses. In the lab, restriction enzymes are invaluable tools for mapping, analyzing, and manipulating DNA.

All restrictions enzymes are named after two things:

(1)  The organisms where they were first discovered.

(2)  When they were discovered.

The first letter of a restriction enzyme’s name references the genus of the ‘source’ organism. The second and third letters reference the source’s species. Following this three-letter genus + species acronym there are one or more letters and/or numbers that reference the strain or serotype. This added reference is essential because bacteria evolve rapidly. Finally, because multiple enzymes have often been discovered in a single strain, the last letters are roman numerals reflecting the order of discovery in that organism. These roman numerals are separated from the genus/species/strain references by a space.

Here’s a breakdown of two popular enzymes: EcoRI and HindIII.

What about the italics? If you look at many restriction enzyme names you’ll notice the first three letters are always italics. That’s because these letters abbreviate genus and species names which are always italics. However, some journals and platforms are forgoing the italics convention in enzymes.

This system was proposed early in the 1970s when scientists were just realizing the potential of these enzymes. It has guaranteed that these workhorses of the molecular biology lab are easy to find and keep track of. It’s also ensured that discoveries made with restriction enzymes are easy to repeat! The full article detailing the system can be read here.

Ever wonder what’s behind the other names you see on your experiment’s component/requirement list? Ask us! Or check back here this fall as we uncover the information hidden in the names of several other biotechnology tools.

Title image attribution: Travis Wise from Bay Area, California, United States, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0&gt;, via Wikimedia Commons

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