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."

Comments

Energy output = input?

[Disoriented]

Now we just have to figure out if the amount of energy needed to synthesize the blood protein (say, X liters of hydrogen in a fuel cell) is less than
the energy of the hydrogen produced from this process... :)

--
Rare 680X0 and PowerPC posters!

Re:Energy output = input?

[Chris Burke]

I'd be willing to bet that this compound can be used to break multiple water molecules, just like our hemoglobin can carry another oxygen molecule after it drops one off. The source of energy that allows continued hydrogen production is the sun.

In which case, the main question is the rate at which you can produce hydrogen. How much of the substance do you need, and how much solar energy, to produce how much hydrogen over what period of time? That is what will define whether or not this is a practical method of producing hydrogen. One obvious point of comparison would be an equal-sized photovoltaic solar cell and water electrolysis machine. If it doesn't do better than that, it's pretty worthless. On the other hand it might be a very efficient way to convert solar energy into hydrogen gas for fuel cells, which would be sweet.

Not to mention the other possibilities it opens up in biochemistry. These proteins are fascinating, as is the idea of swapping out the bound metal atom to get different effects.

Re:Energy output = input?

[Pedrito]

Though it doesn't specify, it's highly unlikely that albumin or porphyrin is used up in the reaction. Instead, it likely cleaves the water molecules (the substrate). Not quite physically tearing it apart, but that probably isn't an entirely inaccurate description either. Many proteins perform functions like this on other molecules. They'll attach to part of the substrate and remove, say an -OH hydroxyl group, or some other piece of the molecule. This is how liver enzymes breaks down certain drugs so that the byproducts (called metabolites) can be removed from the blood by the kidneys. As someone else mentioned catalase from yeast, it works in a similar way and removes an oxygen molecule off of hydrogen peroxide, leaving water and oxygen, but the catalase isn't "used up" in the process.

That said, proteins don't usually last forever and how long they last largely depends on how hostile their environment is, and what constitutes a hostile environment for a protein varies from protein to protein.

Re:Energy output = input?

[sillybilly]

Yes, but most biological matter is easily degraded by UV radiation, plus infection - bacteria would love to feast on your new solar cells.
As a sidenote, to quote the artilce: "Dr Stephen Curry Opens in new window, a structural biologist from Imperial College London's Division of Cell and Molecular Biology who participated in the research explains: "This work has shown that it is possible to manipulate molecules and proteins that occur naturally in the human body by changing one small detail of their make-up, such as the type of metal at the heart of a porphyrin molecule, as we did in this study.
Naturally occur in a human? I was hoping they'd be talking about cow-derived materials, unless they are interested in genetically engineering photosynthetic human beings? Maybe one of our great great grand children will be engineered enough to be vacuum resistant and fully photosynthetic, then he can fly around in outer space while living off of sunshine.

Re:Energy output = input?

[wetfeetl33t]

Yes, that's true if this were a closed system. However, this isn't a closed system. Energy is entering it (from the sun), and mass is entering and leaving (water, hydrogen and oxygen). So yes, total entropy is increasing somewhere, but it just isn't in this hypothetical system

protestors...

[User 956]

The Imperial College in London is reporting that genetically-engineered blood protein can be used to split water into oxygen and hydrogen.

I can hear it now... "No blood for oil! or hydrogen!"

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[account_deleted]

Comment removed based on user account deletion

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.

efficiency

[drDugan]

The mention efficiency many times in the article, but do not mention the most important efficiency number - that is total energy in/out.

So, a quick calculation of efficiency:

FTA

Light in:
6 hours, 450 W light = 2.7 kWh

H energy out:
0.044 mL H ... at 4.7 MJ/L (Wikipedia) * 1/1000 (L/mL) * 1/3.6e6 (kWh/J) * 1e6 (J/MJ) =

= 5.7 e -5 kWh

Disclaimer:

This probably has an error, please help me correct it.

It has been a really long time since I did physics or dimensional analysis.

I could not find in the paper the pressure for the 0.044 ml of generated hydrogen, nor it's weight, so I made a gross assumption the energy density listed in Wikipedia (at 700 bar) was close enough.

Regardless, if you put in 2.7 units of energy and get out 0.000057 units... that seems really (s)low.

Re:efficiency

[TubeSteak]

Regardless, if you put in 2.7 units of energy and get out 0.000057 units... that seems really (s)low

Even if your math is off, it might not matter if the process can be scaled up, since solar power is cheap/free.

The important question is how cheaply can they synthesize the needed protein.

Re:Very exciting!

[Skidge]

The Red Cross can just roll it into their blood drives: "Give a pint of blood and fill up your hydrogen tank!"

Thank you!

[mapkinase]

I would like to praise the submitter for providing a link to a peer-reviewed article. Does not happen very often, worth mentioning.

Next:

[jafac]

We'll need one of these that can split Oxygen and Carbon.

(ie - remove Carbon Dioxide from the atmosphere, and plant the Carbon somewhere safe - like maybe in empty petroleum resevoirs, where it came from).

Re:Next:

[Jherico]

You mean these?

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 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.

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

[CorSci81]

It has, it's called photosynthesis. Granted, here you're not liberating free hydrogen. But to counter the GP argument of using up all water on earth... can you imagine how incredibly unstable the local environment would become for one of these organisms in the wild? They'd be very liable to kill themselves off either through pH changes or simply setting their environment on fire if they reproduced unchecked. That combined with the fact you could never split all the water on earth faster than it will recombine if sunlight is your only energy input.

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

[Coryoth]

I think we (collectively) need to reevaluate the risk factors here; such an organism in the wild could very well turn our planet into a dustbowl in such a shockingly short time we wouldn't even have time to lynch the scientists who created it (think: hours - the mathematics of unchecked reproduction are truly alarming).

Who said anything about reproduction, let alone unchecked reproduction? The article says it is a molecular complex, not a living organism capable of reproduction. I expect it is just an enzyme to catalyse the reaction, so I wouldn't worry about this any more than you would be inclined to worry about naturally occuring cellulase suddenly going rampant and destroying all plant life on earth in a matter of hours. Generally being somewhat informed is a prerequisite critical analysis of risks and any ensuing scaremongering (okay, that's not true, i just think it should be a prerequisite!).

Re:How effecient is this?

[Hubristically Yours]

Not sure about the recombinant albumin, but part of my job involves pharmaceutical purchasing, and a vial of 20mL of 25% human serum albumin can be obtained for approximately $13. The human version is produced by precipitation from donated blood and is used quite routinely in the hospital to treat various conditions such as shock or malnutrition. Also, many medications are packaged with albumin in the vial (to provide a binding surface for the drug molecules).

I would say though that the "manufactured in an industrial scale" statement is a bit misleading. Purified blood proteins in general are ungodly expensive. For instance, immunoglobins, which you might get to protect you against infection if you've been exposed to, say, Hepatitis B or C, are some of the most expensive drugs we have, ranging up into the thousands of $ per shot. Most of these are refined from human blood, but even if you have trillions of bacteria slaving away for you producing recombinant proteins, it's the purification and quality control steps that are the killer.