It appears to be Mahoney Time

This going to be a "cool things I learned in science class" post. You have been forewarned.


This morning in biochemistry class, our professor gave us the Willy Wonka factory tour of an enzyme known as ATP synthase*, which I will now recap even more briefly for your reading pleaure. Trust me, it will be quick and painless, and it's worth following the sci-talk to get to the coolness.

ATP synthase has two components, F1 and Fo.** F1 is a ring of three α-β subunit pairs, and the action happens right in between the two members of each couple. And what action is it? The conversion of ADP and free phosphate to ATP!

(If that doesn't mean anything to you, just think of it as the creation of high-energy fuel for the cell. Good news.)

Anyway, each α-β pair has three configurations - or moods, if you will: liking ADP, liking ATP, and liking nothing at all. They change mood based on the orientation of the γ stick. Don't worry about how it works. The γ stick spins around, pointing to each pair in turn, causing them to like ADP, then ATP, then nothing. This catalyzes the process of turning ADP to ATP and then letting it go.

But, in a Thomist vein (Lewis Thomas, that is, not Aquinas), we have to ask "What makes the γ stick spin?"

Well, that's where the Fo unit comes in. The Fo is a cylinder made up of α-helices, and the γ stick from the F1 sticks down into it like an axle into a gear. The actual dynamics of what happens were beyond the scope of our lecture, but suffice to say that there is a proton pump that that uses the proton gradient across the mitochondrial membrane to make the Fo unit spin. Think of it like a water wheel: because of pumps elsewhere in the membrane, there are a lot of protons outside, so when the Fo's channel opens, they all happily flow in. The Fo uses this current to power its spinning. As the Fo spins, it takes F1's γ crankshaft along with it, clacking the other end across the catalytic α-β pairs and driving the synthesis of ATP.

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If you don't see why this is cool at this point, I'm afraid you may not even see the coolness after I enthuse about it, but here goes:

ATP SYNTHASE IS LIKE A TINY MACHINE INSIDE YOUR CELLS!

Yes, an actual machine. With moving parts. How unbelievably cool is that? I'll tell you: it's very unbelievably cool.

As Julien Offray de La Mettrie wrote in his 1748 L'homme Machine, "The human body is a machine which winds its own springs." Though he was largely concerned with locating the soul in a mechanistic body, I think he would have been ecstatic to know about ATP synthase. Granted we would have had a lot of biology and chemistry to cover before he could even understand what was going on ("OK, so... humours? Right out. Now let's talk about cells...), but this little protein complex really is the perfect example of how mechanical our bodies really are. And because this is a machine involved in creating usable energy for the functioning of the rest of the cell, it's also a fantastic example of the body winding its own springs.



OK, that's enough swooning over science for now. The title of this post, in case you are wondering, is in tribute to the late Professor Mahoney of Princeton's history of science faculty. The man's enthusiasm for machines - and the reading thereof - left a fairly indelible mark on the minds of his pupils, and loomed large over all our explorations into the history of science.





Notes:
*"This is the machine that extracts the juice of the snozberries, and it's connected to the tubes full of luminiferous aether, but it's really rather complicated so don't worry about exactly how it all works. Just trust me, it works."
**That's "F one" and "F oh," not "F zero." The o stands for oligomycin, an antibiotic that poisons the Fo unit.