Blood Protein Used to Split Water

brian0918 writes "The Imperial College in London is reporting that genetically-engineered blood protein can be used to split water into oxygen and hydrogen. The abstract can be viewed for free from the Journal of the American Chemical Society." From the article: "Scientists have combined two molecules that occur naturally in blood to engineer a molecular complex that uses solar energy to split water into hydrogen and oxygen. This molecular complex can use energy from the sun to create hydrogen gas, providing an alternative to electrolysis, the method typically used to split water into its constituent parts. The breakthrough may pave the way for the development of novel ways of creating hydrogen gas for use as fuel in the future."

Re:Energy output = input?

[CorSci81]

Well, we're getting pretty good at genetically engineering simple organisms to produce things like this on their own.... (think BT corn).

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Catalase (cool experiment)

[b0s0z0ku]

Blood also contains a protein called catalase. It makes the hydrogen peroxide that you put on a wounds bubble up with little oxygen bubbles. Yeast contains the same protein. Mix yeast and 3% peroxide solution and you get ------ oxygen and water. Stick a burning match in it and it burns with a bright white flame like a welding torch.

-b.

Doomsday weapon?

[Reality Master 101]

I wonder if you could bioengineer a plant that could survive in the ocean similar to seaweed, which would secrete this chemical. Eventually all the oceans would turn into Hydrogen and Oxygen... and LIFE WOULD BE DOOMED! Bwahahaha

Re:Desalinization

[dextromulous]

If we're lucky, you'd not only get clean water, you'd get an abundance of (clean, perhaps?) energy that could be converted to electricity.

Re:Energy output = input?

[Foofoobar]

Actually they say it far surpasses the current method of separation and assuming this is a passive process (much like solar power), unless the production costs are over a million dollars for one unit, the time it would take to pay for itself is nominal.

Re:We really don't want to do that.

[catbutt]

Given that its from a living thing anyway, it seems like if breaking down hydrogen and oxygen in mass had any survival benefit, natural selection would have figured it out already.

Obviously, caution is always needed in genetic tinkering, but still....I think the knee jerk "OMG its going to zap all our oceans!" is unwarranted.

Re:How effecient is this?

[kebes]

I'm reading over the actual article right now. It seems that process is quite efficient. In the conclusion of the paper they note:

Currently, rHSA(wt) is manufactured in an industrial scale, which allows us to use this zinc-protein photosensitizer in practical applications

Thus the raw materials are cheap enough that one could imagine scaling this up significantly. Moreover since its behavior is catalytic, the protein isn't used up, so you wouldn't need to replace it very often.

With regard to efficiency, in the Abstract they also point out that their system is more efficient than the previous standard in organic photo-synthesis:

The efficiency of the photoproduction of H2 was greater than that of the system using the well- known organic chromophore, tetrakis(1-methylpyridinium-4-yl)porphinatozinc(II ) (ZnTMPyP4+), under the same conditions.

Since the discovered system is a photosensitized catalyst, it effectively is a new kind of solar power. However it is one that directly generates H2 from incident light, without requiring one to harvest light energy as electricity, store it, and then use it to split water. So this discovery, coupled with cars/devices that run on H2 efficiently, seems like a viable idea. Of course we'll have to wait and see whether this really pans out, but from this paper it does indeed seem that this is a feasible way to harvest solar power (and store it as H2).

Biochemical isn't the only approach

[quoll]

I'm pleased to see alternative technologies to split water using sunlight, but the idea is not new.

There is a group at UNSW [sialon.com.au] who have been working on ceramics which use sunlight to split water (via a process of electrolysis). It's still in research (mostly due to efficiency), but it's an interesting option if you're interested in this stuff.

Their website is pretty sparse, but there is a story on them here [abc.net.au].

Where do the electrons come from?

[Draka]

The abstract also mentions "In the presence of the colloidal PVA-Pt as a catalyst and triethanolamine (TEOA) as a sacrificial electron donor, the photosensitized reduction of water to H2 takes place." This basically means that electron fro TEOA is being used to reduce water to hydrogen. This chemical (TEOA) is oxidized and has to be replenished to maintain the H2 production rate. I am not disparaging their results (they are valuable, otherwise it would not be published in such a reputed journal), but trying to put things in perspective. Compare this to the reports of water splitting using titanium dioxide and other ceramics ( http://adsabs.harvard.edu/abs/2006ApPhL..89p3106P [harvard.edu], http://edu.chem.tue.nl/6KM11/files/Project%20repor ts%202003%202004/Photocatalytic%20water%20splittin g.pdf [chem.tue.nl] ) where water is split to yield hydrogen and oxygen without the need for any "sacrificial electron donor".

Re:Desalinization

[hadhad69]

The NaCl in the sea water may interfere with the catalytic pathway in question, its another story altogether really

Porphyrin chemistry is very interesting...

[alchemist68]

Porphyrin chemistry is very interesting and has been studied for over 100 years. This news is both exciting and old news, because porphyrins and related isomers have been the subject of continued research. For very detailed information about porphyrin chemistry, refer to The Porphyrins edited by David Dolphin. Also, review the research of Martin Gouterman. In biological systems, porphyrins are found commonly in heme-type proteins used for oxygen transport and cytochrome P450 in the liver for metabolizing biological compounds including pharmaceutical products, and as chlorophyll in plants. Porphyrins have served as catalysts for organic reactions in industry, photodynamic therapy for cancer, molecular devices including sensors and switches, and model compounds for the active sites of enzymes. My thesis, which available for download through OhioLink:

http://www.ohiolink.edu/etd/view.cgi?akron11339504 18 [ohiolink.edu]

details the photophysical characterization of N-Confused tetraphenylporphyrin and characterization of zinc N-Confused tetraphenylporphyrin.

Upon reading this post on Slashdot, I was pleasantly surprized that the subject of my thesis has some similarities to a related compound that could be used for further research into catalyzing an energy source. In one way I'm surprized, and in another I'm not, and I'm glad that one of the Slasdot crowd submitted the post. Porphyrin chemistry is vast, interesting, and complex.

Happy reading!

Sacrifical Donor

[Roxton]

n the presence of the colloidal PVA-Pt as a catalyst and triethanolamine (TEOA) as a sacrificial electron donor, the photosensitized reduction of water to H2 takes place. [Emphasis mine]
Isn't this a problem? How do you restore the triethanolamine without using energy?

Re:Energy output = input?

[DrFalkyn]

Actually there is somewhat of a point, since the ultimate source of biological energy is the sun, comparing its efficiency to other methods that involve solar is fair game. Unless they are actually talking about putting the protein *in the vehicle*, to produce hydrogen on the fly, then I would be impressed. If you have an efficient way to produce hydrogen from water on the fly, you wouldn't have to have store hydrogen directly which is extremely difficult to stora at the necessary energy densities for vehicular automotion (either needs extremely low temperature or extremely high pressures)

Re:We really don't want to do that.

[maraist]

such an organism in the wild could very well turn our planet into a dustbowl

So why haven't trees stripped every ounce of Carbon Dioxide from the atmosphere?

Because there is more to a chemical process than one input (such as water).. For photosynthesis, there are many chemicals and input sources that are necessary. Sunlight being the most critical element, as it's what provides the energy.

You can do some simple math to figure out how much energy would be necessary in a 100% efficient environment to convert the ocean to Hydrogen and Oxygen.. Then take into account that very little of the high energy solar radiation actually gets to the earth's surface. Then take into account the starvation of constituent ingredients. In photo-synthesis, you need carbon dioxide, Oxygen and water. I don't recall the exact cycle. But for the engine to operate you need to efficiently feed all ingredients in the exact mixture. In nature, this happens through diffusion.. The "waste" products slowly ooze out, while the ingredients seep in (with sun-light permiating based on ideal geographic locations).

Then you have competition between the cells.. They fight over one another, thus starving one or more ingredients. But much like a database deadlock situation. If A blocks B for resource 1 and B blocks A for resource 2, then you have an inpass.

Finally, there are counter-weights in nature. As the chemical makeup of the surroundings change (due to super-saturation of new elements, and th starvation of others'), the ability to do business as usual degrades. The chemical engines themselves, eventually become the food source of some other mechanism.

Thus, even in a homogenous environment of some genetically engineered cellular factory, it would be nearly impossible for the oceans to run dry. SOOOO many factors would kick in LONG before any appreciable progress was made.

Now, it's possible under the right circumstances for a desert's lake to dry up, for example (assuming the right minerals exist to promote cellular replication).

But as other posters have noted, if this were an easy thing to occur, it would have already happened naturally and there wouldn't be water on earth today.

Re:Energy output = input?

[icebrain]

Are we going to look at this from a pure physics standpoint, or a "practical use" standpoint?

Yes, the laws of physics and thermodynamics say that we need to put more energy into the water/methane/$other_hydrogen_source to "crack" it and get hydrogen than we will get back from burning it or recombining it in fuel cells. However, that's not the point. As other posters have said, _all_ fuels take more energy to create or store than they produce when consumed.

You say that "[h]ydrogen is a non-starter, even with this technology. Why? Simple physics: it takes more energy to unbond water than you get back from burning the hydrogen and thusly re-bonding it back into water. Period, end of story. It's a little thing called the Second Law of Thermodynamics. Deal." Again, all fuels require that. Yes, I know that most of that has already been done for us (plants into animals into fossil fuels), but sunlight is FREE. Once we get infrastructure in place, it is (from a _practical_ standpoint) self-sustaining. In other words, we don't have to sit there and pay for every Joule of solar energy we use, because it's going to be there regardless. Might as well take advantage of it.

It's kinda like designing a rocket vs. designing an airplane. When you design a rocket, you have to carry all of your propellant (oxidizer and fuel) with you, and it all has to be accounted for. Every bit of extra fuel or inefficiency hurts you in overall performance. Similarly, when you design a plane, you know that you need air (your oxidizer) to run your engine and to fly. The difference is, however, that you don't need to worry about carrying the air with you. It's everywhere, and you don't have to worry about where it's going to come from. Essentially, it is free. There's a reason rockets define efficiency in terms of total propellant used, while airplanes define it only by fuel used--I don't really care how much air the plane uses, because again--I don't have to pay for it.

I guess what I'm trying to get at is that, at the real-world practical level of things, efficiency is defined as "what you get" over "what you paid for." We don't have to continually pay money for the sunlight to produce hydrogen (which could then power its own distribution costs) like we have to continually pay for the coal/oil/uranium that would be used for the same thing (or that is used in the process of collecting, refining, and distributing themselves).