Page 178 - The Manga Guide to Biochemistry
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Strict Enzyme? Relaxed Enzyme?
Some enzymes are “strict,” which means they only act on very specific substrates.
Other enzymes are more “relaxed” and act on a broad range of substrates.
Strict and relaxed? Sounds like the difference between my mom and my dad...
There are enzymes that can act on substances that are similar or closely related
to their substrates. Many examples of these enzymes are seen in the digestive
system—for example, the protein catabolism enzymes.
Remember, there are a huge number of different proteins. If enzymes were too
specific, there would have to be a separate enzyme to break down every single
kind of protein! Things would get pretty unwieldy.
Only only alanine
glycine and histidine
Strict! Strict!
Since proteins are so complex, the enzymes that break them down had to become a
bit more flexible.
That’s right! Protein catabolism enzymes (the enzymes that break down proteins)
often have a certain degree of leeway in the substrates they can interact with.
164 Chapter 4
