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Our previous tutorial provided a mnemonic to learn the substrates of the citric acid
cycle.
"City Access is the only key to suck a sucky few more orphan cities."
This tutorial explains how to "guess" the enzyme name
based on the name of the substrate that is near that enzyme.
We will do this in four parts:
Part One: You "make" citrate (of the citric acid cycle) with citrate "synthase."
Part Two: The next two do two.
This means that the next two enzymes do two steps each.
"Aconitase" does two steps: it (first) makes and (second) breaks cis-aconitate
So from the mnemonic "city access is the key to" has aconitase 1) before and 2) after "access."
Next, isocitrate dehydrogenase is the second enzyme that does two steps:
Like the remainder of the enzymes, isocitrate dehydrogenase is named after the first thing
before its first arrow, isocitrate.
So this enzyme is "is the, only, key to"
Part Three: More Names before the arrow.
Now it's easier: the remainder of the steps are named based on "what is" before the arrow.
What enzyme does this step?
Before the arrow is "Isocitrate" so the enzyme should be "Isocitrate dehydrogenase"
What enzyme does this step? Before the arrow is "alpha keto glutarate"
so the enzyme should be "a keto glutarate dehydrogenase"
What enzyme does this step? Before the arrow is "Succinyl CoA" so the
enzyme should be "Succinyl CoA synthetase"
This continues for more enzymes: Is The, Key to, Suc A, Sucky, Few, More
"Orphan" really IS in an orphan.
Because "Orphan" does not name an enzyme,
In fact, there are no citric acid cycle enzymes that start with O, either for "orphan" or
for "only"
"What should be" the "orphan arrow" is actually named after citrate, of the citric acid cycle,
and only is named by the second of those enyzmes that do two steps: isocitrate dehydrogenase.
Pause and review.
And visit helphippo.com for more tutorial videos and flashcards.
Our next tutorial in our biochemistry playlist will cover more cellular metabolism details.
HelpHippo: Better than learning from Wikipedia