Using Enzymes to Help Fight CO2 Build-Up

A reader writes to us: "There is a story in the New Scientist that details efforts to use enzymes that destroy ethanol as catalytic converters, turning noxious carbon dioxide into methanol. " The enzymes in question are actually those that are found in the liver - the same one that helps break down alcohol. Cool application of it, if this ever becomes reality.

Comments

Re:This is a joke, right?

[Chemical Serenity]

I would imagine that, aside from sucking down excess CO2 from the oxygen here on earth (which I personally can't see being all that effective in comparison to the diverse and highly efficient ways that nature has already developed), there would be other handy uses for this technology.

Basically, they're advocating using CO2 as what amounts to a chemically-based energy storage unit. Methanol may not be the most human or environmentally friendly substance, but it IS easily convertable back into energy, stable and easy to transport, etc. I could see this technology being used (in conjunction with solar or other more convential power systems) as a method of extracting portable energy to fuel rovers and such on Mars, where there's an abundance of CO2 in the atmosphere waiting to be harnessed.

All very 'blue sky', of course. I'd expect that there's other fuel source methodologies that would be more efficient than this process too.

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rickf@transpect.SPAM-B-GONE.net (remove the SPAM-B-GONE bit)

New Scientist is sloppy: chemistry misses steps.

[Tau Zero]

Step 1: CO2
Step 2: CHOOH
Step 3: CH2O
Step 4: CH3OH

I can't be the only person who noticed that the step from 1 to 2 added 2 hydrogens, step 2 to 3 deletes an oxygen, and step 4 adds 2 more hydrogens... without any mention of where these things are coming from and going to! I'm not a biochemist so I don't know anything about the chemistry of NADH, but a science article ought to at least explain how the equations are balanced.
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Hmmm...

[Josh Guffin]

There is a story in the New Scientist that details efforts to use enzymes that destroy ethanol as catalytic converters, turning noxious carbon dioxide into methanol.

Enzymes that destroy ethanol... noxious CO2 -> methanol...

So basically they're the kind of like me. I break down ethanol with my liver,
and then produce noxious methane (you know what i mean)

=D

Re:Hmmm...

[Tau Zero]

Said SO2, NO2, and H2O all combine in the atmoshere to form H2SO4 and HNO3 and promptly rain down on some forest somewhere, killing it.

One little problem for your assertion there... HNO3 dissociates in water to H+ and NO3-. NO3-, otherwise known as nitrate, is an essential nutrient for plants. It isn't plant-killer, it's plant food. (H2SO3 and H2SO4 have no real uses in that regard, save perhaps for changing the pH of excessively alkaline soils.) The real problem with NOx production is its contribution to photochemical smog.

Nitrate is also produced by lightning, and IIRC the fertilizing effect is well-known. Adding too much puts it into rivers and lakes (promoting eutrophication and algal blooms), but that's once removed from the main issue.
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Hmmm...

[jd]

CO2 is far from being the worst of the greenhouse gasses, and it's already being converted quite nicely into O2 by trees and plants. (Mind you, humans seem to have a habit of turning said trees and plants into lots more CO2 by burning them, to make way for McDonald ranches, in the area formally known as the Rainforest.)

By far the nastiest gasses are NO2 and SO2. These give you that icky brown and yellow smog, which you can see over many industrial cities and major roads during a temperature inversion. They are also the predominant gasses on Venus and are the primary cause of the hellhole nature of that world. They also contribute FAR more to the greenhouse effect than carbon dioxide.

Now, if the enzymes could do something useful with those, I'd be impressed. Clean up smog AND remove the greenhouse effect in one easy sweep. Anyone want to develop a sulpher-based life-form?

Re:New Scientist is sloppy: chemistry misses steps

[aswang]

Here's a theoretical pathway (the real mechanism will certainly be a lot messier, involving enzyme-substrate intermediates):

CO2 + H20 <==> H2CO3
(occurs without catalysis, but can be sped up by carbonic anhydrase)
H2CO3 + NADH + H+ <==> HCOOH + NAD+ + H2O
(catalyzed by formate dehydrogenase)
HCOOH + NADH + H+ <==> HCHO + NAD+ + H2O
(catalyzed by formaldehyde dehydrogenase)
HCHO + NADH + H+ <==> CH3OH + NAD+
(catalyzed by alcohol dehydrogenase)

Net reaction: CO2 + 3NADH + 3H+ <==> CH3OH + 3NAD+ + H2O

I think that's balanced. Biochemists are often lax about mentioning hydrogen ions and water molecules in a reaction because it's generally assumed that they're present in abundance in biological conditions.

Come on!

[QuMa]

Can someone please change em so they make ethanol? Please? (Not that I mind the taste of methanol, it just makes you go blind a lot quicker, and if that happens I can't find my glass).

Re:Another cold fusion-like "discovery"?

[DaveHowe]

They go on about how great this is, and how you can cut down on the amount of C02 into the atmosphere, and it sounds perfect. Until they get to the fact that you need a lot of electrons to make this work. Hess's law states that you can go through any pathway for a reaction, but that the amount of energy is the same in the end. This means that whatever you are burning to create this CO2 must release more energy than the ethanol that you are producing. Seems to me that ethanol releases a lot of energy when it burns. I want to know what type of fuel's CO2 they plan to convert.
*I* wonder how high a percentage of CO2 the mix bubbled through the converter really needs. The problem with electrically powered cars has always been that not enough stored power could be carried for the speed of the motor you want - Motorway speeds will eat all the power you can load onto a mobile base fairly fast. *however*, if you have roadside petrol(gas) stations doing this conversion, you can have the following process:

1. Electricity is produced in non-polluting manner (difficult, I know)
2. At petrol station, electricity+atmospheric CO2 is converted to methanol and stored (continuous process)
3. Cars refuel as normal at station
4. Cars burn fuel, returning the original CO2 to the atmosphere it came from

As far as I can tell, this gives you "clean" electrically powered cars, but indirectly.
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Re:This is a joke, right?

[Tower]

Actually, this is part truth and part myth...
Plants do produce much less O2 during the nighttime, but they do not consume it - they do actually continue the process. Without the added energy of the sun/light source they can only keep this up for so long, but if you check out a book that does a good in depth analysis of photosynthesis and the Kreb's cycle, you should be able to get all of the info there.

Though it used to be common practice in hospitals to remove plants from the patients rooms at night for the very reason you mention - the newer, more accurate research has led to the repeal of these actions.

This is a joke, right?

[fnj]

This is a joke, right? I mean, no one could be so stupid as to think that changing massive quantities of comparatively harmless CO2 into highly toxic methanol is desirable on a large scale.

Methanol is not ethanol. Methanol is toxic when drunk, toxic when the vapor is breathed, toxic when absorbed through the intact skin, and really bad news if you squirt a couple of drops in your eye.

Besides, methanol's only uses are as a fuel and as a raw material for making other compounds. When you burn or catalyze the Methanol as fuel, you get the CO2 back again, and when those other compounds are eventually consumed or destroyed, you get the CO2 back again (and other noxious compounds, by the way).

CO2, on the other hand, is food for plants. If you "cleaned" the atmosphere entirely of CO2, all plants would die, no more O2 would be produced, and eventually all O2 would be consumed and all animals would die. Yes, we are animals, and we would die too.

The New Scientist article is baffling because it seems to have things backwards. Our livers (in the unhappy event anyone is foolish enough to consume methanol - not ethanol) in fact convert methanol into formaldehyde and formic acid, not the other way round. It is this formaldehyde and formic acid that account for the toxic effects - notably permanent blindness and destruction of the nervous system and cerebral cortex (not real fun). I know the article waves its hands and says, oh, the process is reversible. Maybe...

methanol, get drunk cheap!

[radja]

Just go to hospital, first aid department. Wait til you're first in line. and have some methanol handy...

Nurse: what's the matter sir?
you: I'm about to go blind because of methanol poisoning.
(Now is the time to drink some methanol)

The usual way to cure methanol poisoning: saturation with ethanol. Up to the point of getting poisoned by the ethanol.

Disclaimer: If you actually try this you're pretty stupid, so don't come complaining to me (if you can find me on sound and smell)

//rdj