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Wet Fusion

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It turns out that cold fusion doesn't work, as far as we can tell. However, when it was announced, the idea was plausible enough to interest a number of supposedly competent physicists. This means that the idea behind cold fusion, although wrong, is probably only wrong by two or three orders of magnitude.

The thinking behind cold fusion was that hydrogen nuclei, when squeezed into a lattice of palladium atoms, did some quantummy stuff that meant that their wave functions overlapped enough to fuse. The only problem is that it doesn't work, which limits practical applications.

Now, biological catalysts (aka enzymes) do all kinds of clever things. They may also do some quantum things, many people believe. For instance, some enzymes might use quantum tunnelling to speed up certain reactions. The photosynthetic complex in plants is believed, by some, to use quantum smeariness of photons and electrons to achieve its high efficiencies.

Biology is also quite good at handling hydrogen nuclei, aka protons. All the important things in biology happen because ATPases can grab protons and move them using energy from ATP or, conversely, can act as proton-driven turbines to generate ATP. Nature has protons by the balls.

Is it not completely inconceivable, therefore, that an enzyme could do nuclear fusion? It just has to grab a couple of protons (or deuterons or whatever), and get their wave functions overlapping enough for them to fuse.

Unfortunately, fusion is generally bad for living things - the enzyme, if it worked, would be toast. So it would be a single-turnover enzyme. There is also no machinery to harness the energy released, so it's of no use to the cell. Therefore, it would be very surprising if any living thing has evolved a fusionase.

But nowadays we have Science, and we can do evolution the way we want. The following speculation is based partly on very well-established methods in protein engineering.

We want to start with a huge (eg 10^12) library of genes, all encoding proteins that might, just conceivably, do fusion just a teeny bit. Such genes can be made in a combinatorial way, by randomly shuffling and splicing DNA segments that code for parts of existing proton-handling proteins. This part is easy. We then stick this library into bacteria.

So now we have 10^12 different proteins, all of them having some relation to proton-handling, and all being expressed in E. coli (one type of protein in each E. coli). We plate out our bugs, and let them grow up into 10^12 colonies (this needs about a square kilometre of agar, but that's OK - agar is cheap).

Now, 99.999999% of our transgenes will do nothing useful but, if we are very very very very lucky, a handful of them will sling protons (or deuterons - we can provide D2O) around in such a way as to favour fusion. Note that fusion does happen very, very rarely in many situations (it's statistical, and just incredibly rare), but we're looking for some increase above the very low background rate.

So, we monitor our square kilometre of agar, looking for fusion events and noting where they come from. We find that a handful of our 10^12 bacterial colonies are producing fusion events at a low but significant rate. Great!! We're in business!!

We now pick those colonies that give any hint of fusion, and do random mutagenesis on their transgenes, and go through the whole process again, now hoping to find colonies (hence proteins) that fuse a little better.

Et cetera, et cetera.

Eventually, we end up with a tenth-generation protein that can do fusion at a half-respectable rate.

All of the above is exactly what people do when trying to evolve other types of catalytic activity, but there are a couple of twists.

First, as mentioned, successful fusion will destroy the enzyme, so we'll only get one fusion event per enzyme molecule. That's OK though, because a single bacterium can make hundreds or thousands of copies of the protein (and we have lots of bacteria in each colony, too).

Second, successful fusion might kill the bacterium. Initially, this won't matter: we'll be looking at a colony of maybe 10^7 clonal bacteria, and detecting maybe 10 or 100 fusion events at most; most of the (identical) bacteria in the colony will survive.

But is it certain that a fusion event would, in fact, kill the host cell? A fusion event will release about 20MeV of energy, or about 3 x 10^-12 Joules. Even if all of this gets absorbed by the bacterium as heat, that's only enough to raise its temperature by 1°C. So, although there'll be some localized damage, there's a good chance that the individual cell would survive the occasional fusion event, which is nice.

Would all this be of any use? Well, we're going to get a maximum of maybe 100 fusion events per minute per bacterium (since the protein has to be replaced every time it fuses). A dense bacterial culture is roughly 10^12 cells per litre, so a litre flask would give us 10^14 fusion events per minute, producing about 1/3rd of a joule of energy. That's about 50mW of heat. So no, not very useful, but very cool.

MaxwellBuchanan, Oct 24 2017

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       It sounds like you could also generate a time machine using the same approach.   

       How many buckets of agar to a tiny (the smallest) fusion reaction?
mylodon, Oct 24 2017
  

       _Deinococcus radiodurans_ is remarkably resistant to ionising radiation, being able to withstand "an acute dose of 5,000 grays ... with almost no loss of viability", if Wikipedia can be believed.   

       It also has "a diameter of 1.5 to 3.5 µm". Let's assume a little 'un of 1.5µm diameter; if it's mostly water, it has a mass of 1.77*10^-15 kg.   

       1 Gy of dose corresponds to 1 J/kg. This means that a single event of 3x10^-12 joules, if completely absorbed within the bacterium, deposits about 1700 Gy of radiation.   

       This suggests that an individual of _D. radiodurans_ should be able to survive a turnover of your proposed fusionase, given sufficient time to allow its self-repair mechanisms to operate before the event is repeated.   

       //That's about 50mW of heat. So no, not very useful...//   

       ...until we sequence the bacteria, reverse-engineer the structure of the enzyme, mass-produce it, and feed it into the reaction as a consumable without having to worry about the lifetime of all the pesky bits of bacterium which produced it.   

       (Is it ethical to evolve these beings for the sole purpose of letting little deuterium-fuelled party poppers off one at a time, patching themselves up, and soldiering on? I'll leave that question to the vegans.)
Wrongfellow, Oct 24 2017
  

       //reverse-engineer the structure of the enzyme, mass-produce it//   

       Yes, but you'd mass-produce it using bacteria, wouldn'tcha? So, it would probably be more economical just to grow the bugs.
MaxwellBuchanan, Oct 24 2017
  

       Wouldn't that depend on how long they take to recover from the 'explosion' vs how quickly they can grow in the absence of being blown up for a living?   

       Besides, we won't know how to mass-produce it until we've reverse- engineered it, so can we just have a bit more budget and get back to you, please?   

       (Personally I wouldn't consider using bacteria until I'd asked [8th] for an up-to-date copy of his wholesale catalogue.)
Wrongfellow, Oct 24 2017
  

       First you should breed microbes (bacteria, atoms, particles, whatever) that are increasingly more likely to win lotteries, then win the lottery, which will take care of the funding. And a nice holiday.
Ian Tindale, Oct 25 2017
  

       If fusion was possible in cytoplasm wouldn't nature have got there first? Maybe the gut bacterial didn't evolve fast enough for the dinosaurs to make it through the cold.   

       I think some more keys on the enzyme structures and more importantly ideal spacial conditions are needed to cut down the vast blind start. How about a scaled up 'protosynthesis', proton catch, as a starting point.
wjt, Oct 25 2017
  

       // If fusion was possible in cytoplasm wouldn't nature have got there first?// It's possible, but the energies involved aren't easily harnessed, so it might never have taken off. Also, who knows, maybe some psychrophilic bacteria do use fusion to stop themselves freezing to death.   

       //cut down the vast blind start// Yes and no. By starting with bits of protein that already have something to do with proton handling, we're actually getting a headstart (like trying to evolve a clockwork mouse, and starting with a lot of springs and clock parts instead of completely random hardware). The trick with directed evolution is knowing how much knowledge to leave out of the initial conditions, without making your search space unneccessarily vaster.
MaxwellBuchanan, Oct 25 2017
  

       //hydrogen nuclei, aka protons//   

       Won't somebody think of the neutrons?
pertinax, Oct 25 2017
  

       Oh no. Bugs going nuclear. That can't be good somehow. Biochemical nuclear weapon?
RayfordSteele, Oct 25 2017
  

       // Biochemical nuclear weapon?   

       Maybe the fusion gene could be put in a strain of E. coli that's been engineered to bind to colon cancer cells. Although self-heating pond scum could be useful, too.
Cuit_au_Four, Oct 25 2017
  

       Don't believe atoms - they make up everything.
normzone, Oct 25 2017
  

       Yes, I know. I don't need electron the subject.
MaxwellBuchanan, Oct 25 2017
  

       // self-heating pond scum could be useful, too. //   

       Indeed, the Democrat party HQ could save a fortune on heating bills.
8th of 7, Oct 25 2017
  

       If it ducks like a quark…
Ian Tindale, Oct 25 2017
  

       making up all the numbers, based on the studies so far cold fusion is only wrong at p<.000...01 , so just for fun have palladium metalloproteins that do things to protons to up the odds.   

       Good thing an AI will someday read the halfbakery...
beanangel, Oct 25 2017
  

       // do things to protons //   

       Why ? Protons aren't useful. You need deuterons ... if you have tritium in the mix, maybe you can use fast protons to make Helium-3, but what you really need is lithium deuteride.   

       Thing is, deuterium has a measurably different biological activity to protium - sufficiently so that heavy water exhibits significant toxicity to many organisms.
8th of 7, Oct 25 2017
  

       If only someone had mentioned deuterons in, oh, say the tenth paragraph of the idea.   

       Heavy water is somewhat toxic, particularly to eukaryotes. However, most bacteria will survive in almost pure D2O (plus, of course, the necessary sugars and whatever).
MaxwellBuchanan, Oct 25 2017
  

       //If it ducks like a quark…//   

       And so, one of the greatest possible puns of all time is sadly let down by fact that quarks do not, in fact, duck under any plausible circumstances.
MaxwellBuchanan, Oct 25 2017
  

       //// If fusion was possible in cytoplasm wouldn't nature have got there first?// It's possible, but the energies involved aren't easily harnessed, so it might never have taken off.////   

       Well, there is a suspiciously high level of deuterium in the oceans... Current best theory is that comets provided the water and they're high in deuterium. Sounds a bit far fetched... perhaps as far as the Oort cloud.   

       //A dense bacterial culture is roughly 10^12 cells per litre, so a litre flask would give us 10^14 fusion events per minute, producing about 1/3rd of a joule of energy. That's about 50mW of heat.//   

       so if sustained for an hour, that's 0.00005kWhr of very low grade heat, assuming an optimistic 50% conversion efficiency and $100 for half a kilo of LB* that's just under $50,000/kWhr. Which is frankly dirt cheap compared to ITER. AND, the anti nuclear brigade will love the self- limiting (65C and it's not doing anything again) bio-fusion marketing campaign. If you were being clever, you could design a co-operative binding system so that 3 protons bind, on the 4th, you get a conformation change that does the lot all at once.   

       Sadly, it looks like biology uses the "Grotthuss" mechanism, H+ isn't free, it jumps onto water to make H3O+, hydronium, which further stabilizes into Eigen cations (H2O)3H3O+, which seem unrealistically huge at 0.1nm or so. The proton can continue jumping from water to water or until it finds an even more friendly amino acid side chain.   

       *I always thought I'd have got around to a bloody good optimization of that stuff by now. Nowhere near enough calcium/magnesium/phosphate. Where's clever self- precipitating system, a K+ionophore or something?
bs0u0155, Oct 25 2017
  

       //H+ isn't free, it jumps onto water to make H3O+, hydronium, which further stabilizes into Eigen cations //   

       Yes, but we don't want our H+ (or D+) to be free. We want it all confused in some sort of quantum delocalized system, such that it finds itself in almost the same place as another D+ (or H+) from time to time, and fuses. The most important part of the process is the arm-waving.   

       And I thought optimised LB was SOC?
MaxwellBuchanan, Oct 25 2017
  

       // Heavy water is somewhat toxic, particularly to eukaryotes. However, most bacteria will survive in almost pure D2O (plus, of course, the necessary sugars and whatever). //   

       Hmmmm ...   

       What about yeast ?   

       Now ... could you engineer an enzyme into yeast that captures deuterium, due to its different physical chemistry ? Then incorporate the deuterium into alcohol.   

       Normal water is about 0.01% "heavy". Even if only two hydrogen atoms in each ethanol molecule are deuterium, that's a very significant enrichment of the concentration.   

       Feed in sugar and water. Keep the medium warm. Vacuum - distill the deuterated alcohol. Burn it for energy to drive the process, condense the water, feed it into the next fermenter in the chain. Blow the CO2 into a huge greenhouse full of sugar cane, or beets.   

       At the end of the sequence, bottle and sell heavy water.
8th of 7, Oct 25 2017
  

       //could you engineer an enzyme into yeast that captures deuterium//   

       I don't see why not. The *slight* toxicity of deuterium is due to its different chemical behaviour, so it should be possible to make deuterium-selective enzymes.   

       One problem would be devising a selection strategy, or even a screening strategy at a pinch.
MaxwellBuchanan, Oct 25 2017
  

       Isn't that HR's job ?   

       <aside>   

       // until I'd asked [8th] for an up-to-date copy of his wholesale catalogue. //   

       Hi [Wrongfellow], just letting you know that a copy of "Electronic Service, Unit #16" is in the mail to you.   

       </aside>
8th of 7, Oct 25 2017
  

       I like the idea but think that a quantum environment is vastly different from a few quantum effects that aid an enzyme pathway. If it is possible, the enzymes to create this new intracellular space will come way out of left field. Not so much a clockwork mouse rather a steam powered mouse.
wjt, Oct 25 2017
  

       //possible to make deuterium-selective enzymes//   

       Well deuterium dissociates less readily compared to normal protons, so it behaves as though it is pH shifted ~0.4. So take a survival critical enzyme, specializing in hydrolysis preferably, and replace it with one from any pH shifted organism you like and then just tune the pH to suit.
bs0u0155, Oct 25 2017
  

       [marked-for-tagline]   

       // only wrong by two or three orders of magnitude //   

       // The only problem is that it doesn't work, which limits practical applications. //
BunsenHoneydew, Oct 30 2017
  
      
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