Chemistry World Podcast - November 2006
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Brought to you by the Royal Society of Chemistry, the Chemistry World Podcast.
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Interviewer - Chris Smith
Hello! Welcome to episode 2 of the Chemistry World podcast with me Chris Smith, with Chemistry World Editor Mark Peplow...
Interviewee - Mark Peplow
Hello!
Interviewer - Chris Smith
Deputy Editor, Bea Perks...
Interviewee - Bea Perks
Hello!
Interviewer - Chris Smith
And science correspondents Richard Van Noorden...
Interviewee - Richard Van Noorden
Hello!
Interviewer - Chris Smith
And Victoria Gill...
Interviewee - Victoria Gill
Hello!
Interviewer - Chris Smith
In this edition: Should you be worried about what's chemically creeping onto your dinner plate. Toxicologist, John Henry, says not.
Interviewee - John Henry
Personally, I'm very concerned that there are so many people clamouring about the chemicals that we are constantly eating.
Interviewer - Chris Smith
Also, if you thought the dark side was something only found in Star Wars, then be afraid because it also applies to proteins including the ones inside your head.
Interviewee - Philip Ball
There seems to be a sort of a dark side, I suppose, of protein folding. Many proteins are also very adept at misfolding into a completely different sort of structure that can have pathological consequences.
Interviewer - Chris Smith
And also how an old technology is helping coal to clean up its act.
Interviewee - Andrew West
The sort of basic definition of clean coal technology is the conversion of a lump of coal into a gas, syngas, by using the old coal gas technology that existed way back in the early 19th century.
Interviewer - Chris Smith
There'll be more from Andy West on the science of clean coal technology, coming up shortly. First though, listener's to last month's podcast, will recall Monica's question about how a piece a coal added to her lettuce helps to keep it nice and crisp, just in case you've forgotten, here's a reminder.
Interviewee - Monica
I've got into the habit of putting a piece of coal in a bowl of water with my lettuce. This seems to crispen up the lettuce and I'm wondering why that might be?
Interviewer - Chris Smith
So, Mark, have you found us a solution to this one?
Interviewee - Mark Peplow
We worked very hard on trying to find the solution for this one and you'll know that Monica was using a piece of coal in a bowl of water with the lettuce to help crispen it up. All the experts we talked to told us that surely adding limp lettuce to a bowl of water was indeed a good way to crispen it up; the coal however, no idea. Nobody knows what that's actually doing or in deed whether it's actually having any effect?
Interviewer - Chris Smith
Or just giving some one cancer?
Interviewee - Mark Peplow
Indeed. And the reason why the water works is because all the cells in the lettuce are like little bags of fluid. When they lose fluid, they become limp and saggy, so your lettuce becomes flaccid, but if you actually can get water back into those cells, it makes them rigid again, makes them stand up stiff and straight and it makes the lettuce crisp.
Interviewer - Chris Smith
But you've decided to do a little bit of experimentation.
Interviewee - Mark Peplow
Well that's right. It wasn't enough for us to just talk to experts. So we actually set up an experiment in the studio and we are going to actually watch to see if there's any difference between having limp lettuce in a bowl of water and limp lettuce in a bowl of water with some coal.
Interviewer - Chris Smith
Thanks Mark. You'll just have to let us know what happens later in the program. First though, news that Russian scientists have created the world's largest element, Richard!
Interviewee - Richard Van Noorden
That's right Chris. You can take out your periodic table and pencil in one more element, element 118.
Interviewer - Chris Smith
So how did these guys do it?
Interviewee - Richard Van Noorden
Well, they smashed a californium target with a beam of calcium ions, hoping to fuse the two ions together to create an extra heavy element at the Joint Institute for Nuclear Research in Dubna, which is one of the big particle accelerators of the world.
Interviewer - Chris Smith
Have they made significant amounts of this stuff or is it just a tiny fraction of what they could make
Interviewee - Richard Van Noorden
Just three atoms, I'm afraid so far. It does support the creation of one atom back in 2002, which was suspected. So now we have four atoms in total.
Interviewer - Chris Smith
But what can you actually do with this stuff? Why is this important?
Interviewee - Richard Van Noorden
It's so short-lived, you can't do any chemistry, but hopefully it will tell us something about the internal structure of the atom.
Interviewer - Chris Smith
But why is it significant that it is number 118?
Interviewee - Richard Van Noorden
Well, the previous nucleus record was 116, and now they've gone up to 118, which is two more, apparently it's very difficult to get 117 due to the atom structure and they're going to go for 120 later on.
Interviewer - Chris Smith
So what are we hoping to learn out of this? You said a bit about structure, but what really is the nub of this?
Interviewee - Richard Van Noorden
Sure. Well, physical theory suggest that atoms with a particular number of protons and neutrons are magic combination, will be stable and will hang around for a long time; 118 only hangs around for less than a millisecond. By getting heavier and heavier atoms, may be we can get to the point where we can actually make these stable elements in the laboratory and support our theories.
Interviewer - Chris Smith
Thanks Richard. Well from heavier elements to thermoplastics now. And good news even for people who have the most jaundiced view of polymers and that's because these ones are made of bile, Victoria?
Interviewee - Victoria Gill
Yeah that's right. Its sounds a little bit gruesome, but polymer chemists have managed to use our indigestive chemicals now to make thermoplastic elastomers, which are very useful as surgical tools for things like internal stitches.
Interviewer - Chris Smith
So you're going to say in elastomers making corks because corks in wine bottles are popularly made from elastomers these days, well, aren't they?
Interviewee - Victoria Gill
All right, well these ones are pretty specific. These ones are for surgical and medical use, so things like internal stitches to fix cartilage, which is notoriously very difficult to mend if you've torn it.
Interviewer - Chris Smith
I suppose the benefit being that it's made from stuff that's already found naturally in the body and is therefore more biocompatible?
Interviewee - Victoria Gill
Yeah, that's exactly, they've managed to polymerize monomers out of bile acid. What they've done is they've used ring opening metathesis, they haven't' been able to do it before with these particular monomers, because they were too big and the ring structures were very difficult to break, but using a Grubbs' catalyst, they've managed to make these polymers that are elastic, thermoplastic and degradable and when they degrade, they make non-toxic substances that are found in bile acids so they are compatible with the human body.
Interviewer - Chris Smith
But they haven't actually been tried in vivo yet.
Interviewee - Victoria Gill
No, not yet, but they are very excited about the possibility of them used in medical applications.
Interviewer - Chris Smith
And will it be possible using this technique to make reasonable amounts or does it give such a low yield that is not actually going to be very easy to do that.
Interviewee - Victoria Gill
No, actually that's one of the things they are particularly excited about. It's a very good yield and also bile acid is something that can be produced in large quantities, they can take it as a waste product from the meat industry. So there is huge quantities of it available to make this stuff.
Interviewer - Chris Smith
This sounds like very good news. Well thanks, Victoria. Now from a chemical that should be in the body to the one that certainly shouldn't, Mark.
Interviewee - Mark Peplow
Yeah, that's right. If you've been reading the papers recently, you may have heard that apparently the food that we eat in Europe is contaminated with a wide range of substances from brominated flame retardants that are used to stop your sofa going up in flames to polychlorinated biphenyls. This is news coming from the WWF, a report accompanied by press release entitled, 'waiter, there's a phthalate in my soup!'. Funny enough, WWF have been running very similar stories for the last 3 or 4 years testing celebrities for trace contaminants in their blood. Every time it's a big media success for them. The truth of the report is that they are finding nanograms per hundred grams of food of these contaminants. Now that's acknowledged widely by, for instance, the Food Standards Agency to be well below what might pose any risk and in fact scientists are quite unimpressed with this report.
Interviewer - Chris Smith
Well, to try and find out what's going on, I went and asked clinical toxicologist, John Henry, who works in Mary's Hospital in London about his reaction to the claims.
Interviewee - John Henry
Personally, I'm very concerned that there are so many people clamouring about the chemicals that we are constantly eating. Interestingly, these are the synthetic chemicals that they concentrate on. There are many natural chemicals that we also eat in nanogram amounts, ones that are not easily biodegradable, but nobody pays any attention to those, but what they are concerned about is the synthetic chemicals that remain in small traces; they are at parts per billion amounts, they are extremely small concentrations. There is no evidence at all that they have any effects on life on this planet.
Interviewer - Chris Smith
But John, the absence of evidence, isn't the same as they are being a safe track record for these compounds, is that? So, I think, don't people want some kind of reassurance that even if there is something present only at a tiny amount, it's not having any kind of toxic effect on their body in the long-term?
Interviewee - John Henry
I accept that the absence of evidence doesn't really prove that there is nothing happening. On the other hand, we have the experience of many of these chemicals that have been around for 40 or 50 years and we have no evidence of harm from them. It is very difficult to test the effects of minute amounts of chemicals, really, the only way you can do it is by long-term epidemiological studies and at the moment there are no warning signals on the horizon.
Interviewer - Chris Smith
But don't you think that we should, at the same time, if we are introducing a new chemical into the environment, push it up the agenda a little bit in terms of assessing how it interacts with people and animals in the environment.
Interviewee - John Henry
We should test how things interact, but at the same time, many of these studies would take years. Animals are very poor models for humans, in this kind of field. So, our ultimate experimental model is man and that means that we have to use epidemiological handles, which take years and years and years, when we look at these chemicals, we can't even find a mechanism by which picogram amounts are going to have any effect.
Interviewer - Chris Smith
So, your reaction to the WWF's approach to this is what?
Interviewee - John Henry
My answer to WWF, who are on this campaign to point out these minute amounts of chemicals is, look at what these chemicals are doing, for human progress. Millions of lives have been saved by the use of DDT, hundreds of lives have been saved by the use of flame retardants and balance that against a theoretical risk with no evidence of harm and the scale tilt very strongly.
Interviewer - Chris Smith
John Henry reacting to claims from the WWF that our food is contaminated by traces of industrial compounds. Over to Stockholm now and you've been looking at this year's Nobel Prizes Bea.
Interviewee - Bea Perks
Yes, this year's Nobel Prize in Chemistry went to Roger Kornberg at Stanford for his work on eukaryotic transcription. Eukaryotes were essentially organisms who keep their genetic material in nuclei and what he managed to do, in fact he worked on yeast because yeast are much easier to culture. He actually managed to get in one image transcription in action, so he sees the DNA template that comes out of the nucleus, RNA polymerase II bound to the DNA, which then creates this messenger RNA template from the original DNA templates. So, the RNA then goes onto to act as the code for the proteins that are made by the genetic information.
Interviewer - Chris Smith
And he got all of this in one shot.
Interviewee - Bea Perks
He got all this in one shot, I mean, it was not an easy job. Really tens of thousands of litres of yeast he had to go through. I think, he was, over a decade, actually waiting for to find something. He had to just keep going at it, year after year nothing and where most people would have said, "fine we can't do this,". He carried on and he got it and it really is an amazing shot.
Interviewer - Chris Smith
And wildlife photographers think they have a hard time when they have to spend 6 months in a mountain side to capture sort of 5 seconds of footage, but that really does push the boat doesn't it, but why is this actually chemistry, because a lot of people will say well that's biology, isn't it?
Interviewee - Bea Perks
Well quite. I mean, he is a professor of structural biology, but what this goes to show more than anything is how the borders between sciences are so broad now, it really was chemistry, no question it was chemistry. Aaron Klug, actually he won the chemistry Nobel in 1982, I think. This completely is chemistry. It's a chemistry of big molecules, I mean, these are huge molecules, a great big polymerase enzyme, a strand of DNA, a strand of RNA, this is a really quite macro stuff, but now totally its chemistry, but it informs biology.
Interviewer - Chris Smith
There have been a few bones of contention about who has won some of the prizes this year, haven't they?
Interviewee - Bea Perks
Absolutely! Yes, apparently there's been quite a few chemists saying 'Oh no! You know, it wasn't really a chemistry prize at all, it was a biology prize'. Even then people in Germany saying "well how come it's always American that won," Roger Konberg is an American, but there's only going to be one Nobel Prize for any subject and there's going to be an awful lot of people who could conceivably have won it. Actually it was interesting. I was reading the other day, Francis Crick's biography by Matt Ridley, and he said that if perhaps, if Rosalind Franklin had lived to see the 1962 Nobel Prize go to Watson, Crick and Maurice Wilkins, perhaps we can't give the prize to four people, obviously it couldn't have gone to Rosalyn Franklin because she was dead, but if she'd been around, perhaps they would've split it, he was saying, perhaps they'd have split it and Rosalind Franklin and Maurice Wilkins would have got the chemistry prize, so whereas Watson and Crick got the Medicine or Physiology prize, so it is this very very grey area and this all comes down to Nobel's Will that he wrote in 1895, when he just said chemistry, medicine and physiology and physics and really science isn't delineated like that these days.
Interviewer - Chris Smith
Now from one kind of macro molecule to an entirely different one and the subjects of proteins and how they're tying themselves in knots. Here, with the first of a regular series of columns for Chemistry World science writer, Philip Ball untangles the science of amyloid.
Interviewee - Philip Ball
The idea that we have about proteins is that they are these polymers that are fantastically well tuned to fold into particular shapes that enable them to act as catalysts and that's precisely what they do for most of the time, but it's become clear in recent years that there seems to be a sort of a dark side, I suppose, of protein folding, that many proteins are also very adept at misfolding into a completely different sort of structure and that this is one that can have pathological consequences, that seems to be what happens in a lot of neurodegenerative diseases.
Interviewer - Chris Smith
Such as things like Alzheimer disease?
Interviewee - Philip Ball
Absolutely yeah. When there's a whole class of diseases that seem to be linked to this general problem; Alzheimer's is probably the best known and it has been known for a long time now, but what seems to be happening now in Alzheimer's is that you get these kind of aggregates of protein junk that forms in the affected neurons and in somewhere or another that, I think is not completely understood, screws up their function, so the question is where did these protein aggregates come from, why do they form and that seems to be an expression of this dark side of protein.
Interviewer - Chris Smith
I suppose the other question Phil is why don't they form more often because these kinds of things, Alzheimer's disease being one of them, tend to occur late in life and will be on the selective pressure of sex.
Interviewee - Philip Ball
Well, in a way that seems possibly to be the key to what goes on here, the fact that they seem to be operating sort of outside of normal selective pressures. The idea here is that evolution has identified protein sequences that have this propensity to misfold and has tended to eliminate them and there was some work done several years ago by Michael Hecht of Princeton, and colleagues who identified protein sequences that seemed to be particularly apt to misfold in this way and then they found, looking through these structural database of proteins, that that's a very rare structure in proteins so it does seem as though that there has been some weeding out by evolution to get rid of these dangerous protein sequences, but nevertheless, when, if you like evolutionary pressures gets relaxed in old age, you know, where we have sort of outlived our evolutionary use, that's when some of these problems do start to arise.
Interviewer - Chris Smith
Is there anything we can actually do about it, because you know, it very well as being able to say "well, we know these proteins do this," but is there a way to throw a spanner in that work and stop the proteins taking on this abnormal configuration?
Interviewee - Philip Ball
Well, it's very hard to say how one might do that because, you know, it is something intrinsic to the protein structure itself. I mean, I'm sure there are other ways of redressing the disease, I mean, obviously stem cells is one of the key technologies that people are hoping is going to be able to enable us to regenerate damaged neurons amongst other tissues, but I guess you could look from this as having a bright side, in the sense that these misfolded proteins, these aggregates that form actually have a very similar structure in some ways to silk, which is a protein where this particular kind of folding has a positive benefit, it seems that the misfolded proteins are very strong and very stiff and that puts a good use in silk and so it appears that it may be possible at least to sort of exploit this tendency for proteins in making new peptide based synthetic materials that have these very good mechanical properties.
Interviewer - Chris Smith
Are there any which fit that bill yet?
Interviewee - Philip Ball
Well, people have certainly been trying to make synthetic silks of one sort or another for many years and the thinking has tended to focus on the idea that you somehow have to pretty much mimic silk's protein sequence or something close to it, but now that the mechanical properties of the fibrils, these protein aggregates in Alzheimer's, now that they've been studied and seem to have silk-like properties, that raises the possibility that actually we don't have to be that specific about the protein sequence in order to get these silk-like proteins. So actually there might be whole classes of protein that will fold in to these structures.
Interviewer - Chris Smith
Chemistry World columnist, Philip Ball discussing the first of his series of articles, this month's being on the subject of 'How Proteins are Tying Themselves in Knots'. Now there's really good news for new way to look deep inside cells using mass spectrometry. Mark.
Interviewee - Mark Peplow
That's right. This is a fantastic new technique that's been developed by a couple of groups in the States. Basically it's giving you a new window on cells that's neatly between these sort of conventional optical microscope, where you can see a certain amount of detail about a cell and atomic force microscopy, which can give you resolution on the molecular scale within cells. Now what these two groups have done, Claude Lechene at Harvard and Steven Boxer at Stanford are to use a beam of ions. It's like a machine gun firing caesium ions at a biological membrane and what they do is look at the fragments of debris that scatters off that membranes, say, and they use that to construct an image of the molecular surface. What's more, they can actually get chemical information about the surface at the same time, so you're taking a picture, but you're also finding out what the stuff is made of.
Interviewer - Chris Smith
Is it just confined to looking at the cells surface though, Mark or can it probe deeper within the cell, because, that of course, would be more useful?
Interviewee - Mark Peplow
Well, this is the thing. Boxer actually tested this out by making artificial lipid membranes, but Claude Lechene has actually been able to look inside cells as well. What he did is feed mice, for example, with amino acids that were labelled with specific isotopes. Those incorporate themselves into different parts of the cell tissue and then by firing this beam of caesium ions at the cell and saying, which were the isotopes come out, you can actually discern structures from within the cells, well you can actually watch them moving around.
Interviewer - Chris Smith
So the technique doesn't actually destroy the cell in the process. You can get real time data.
Interviewee - Mark Peplow
You can get real time data, that's exactly what Claude Lechene did.
Interviewer - Chris Smith
It's exciting stuff. Well, unfortunately though there's been a setback in the quest for trying to find a drug to bust out gut line, Victoria.
Interviewee - Victoria Gill
Yeah that's right. Another obesity drug bites the dust, I'm afraid. Merck, the drug company in New Jersey in the US, have been carrying out clinical trials with a new drug called MK-0557, catchy name. Steven Heymsfield has been leading the group and he has been testing a new drug that acts by suppressing a neuropeptide which is a chemical that stimulates appetite in the brain, it's called neuropeptide Y, this drug produced very very promising results in rodent studies, but now they've taken it to clinical trial and it's really disappointed.
Interviewer - Chris Smith
So, the idea here is that this drug blocks the sort of feel-good part of the brain, that's appetite promoting.
Interviewee - Victoria Gill
Yeah, it blocks the part of the brain that stimulates your appetite that says that you are hungry, that sends messages to your stomach that you are hungry and you want to eat.
Interviewer - Chris Smith
So it sounds intuitive to think that it would work in humans. Have they given any clues as to why it hasn't?
Interviewee - Victoria Gill
Well, that was the thing; it did work, but only a bit. It produced some very small minor results in humans, but they used the phrase that results weren't clinically relevant. And what Steven Heymsfield told me is that looking at one pathway of chemicals is not enough in a human. There were too many different systems going on when you are talking about appetite and food and particularly when you are talking about obesity. At the same time, another group in New York, have been doing some tests on human subjects, where they've used a gastric stimulator like an electrical stimulator that stimulates the stomach because the stomach thinks it's full and sends a message to the brain. Then, what they were doing was using a magnetic resonance imaging to take images of the brain to see which areas of the brain are lighting up or active when you get the stimulation to say that you are full and the interesting thing was it's not just that part of your brain, the hypothalamus, the satiety centre that is lighting up, its other parts of your brain associated with things like addiction and pleasure, so there were so many more complex, psychological elements to obesity, so one drug suppressing one neuropeptide is not going to be effective in humans alone.
Interviewer - Chris Smith
Thanks Victoria. That's the NPY of why Merck's experimental new fat-fighting agent MK-0557 seems to have bitten the dust in clinical trials. Well, from one form of energy, the energy found in the body to energy on a grand scale, the energy we get from coal. Environmentally speaking, coal is a filthy fuel, but that could be about to change. Thanks to clean coal technology. To tell us more, here's the Chemistry Innovation Knowledge Transfer Networks,' Andy West.
Interviewee - Andrew West
The sort of basic definition of clean coal technology is the conversion of a lump of a coal into a gas, syngas, by using the old coal gas technology that existed way back in the early 19th century. The technology has the advantage of becoming more environmentally friendly, because rather than just burning of a lump coal and releasing all the soot and sulphur compounds, all the nasties that the lump of coal contains, if you turn it into a gas first, first of all it's much easier to clean the gas and secondly you're not going to carry any of the soot or other particles through when you burn the gas for energy generation.
Interviewer - Chris Smith
Now how much coal do we actually use in the UK every year and what percentage of our energy does it supply?
Interviewee - Andrew West
We use millions of tons of coals, as you can imagine, most of our power stations, a vast majority, I think, somewhere around 70% of our power stations are coal fired at the moment.
Interviewer - Chris Smith
So, it's a significant amount, isn't it?
Interviewee - Andrew West
This is a massive amount, yes.
Interviewer - Chris Smith
So, is it relatively easy to upgrade our coal-fired power stations, so that they can use this as a gas rather than actually burn physical blocks of coal?
Interviewee - Andrew West
There is a problem with this. The main disadvantage of converting from coal-fired power stations into these syngas-powered power stations would be that there would obviously have to be some retrofitting used, but it stands we don't have that many gas-fired power stations which will be able to use syngas directly, so there would be problems with having to upgrade our existing power stations.
Interviewer - Chris Smith
And when you actually do this reaction, you use what, air or oxygen and you add that to the coal? What's the product and how does it actually work to be beneficial to the environment?
Interviewee - Andrew West
Okay, as you said, you pass steam or hot oxygen over a lump of coal and partial combustion occurs, which basically converts carbon chains in the coal into carbon monoxide and hydrogen gas, which is also well known to chemists as syngas and this can then be used for energy generations as though you were burning the coal, but you're just going to burn this gas instead.
Interviewer - Chris Smith
But the problem is, doesn't it leave behind a lot of coal residue, which presumably you then have to try and deal with, and that's equally bad for the environment, isn't it?
Interviewee - Andrew West
It is, I mean, yes you do end up with lots of residue left behind. The advantage is that, of course, it's trapped and you can deal with it, it's sitting there and it's very easy to cope with. It can also be used in things like tar formation or it could be used as filler in plastics. There are other ways of getting away from actually having to just bury this nasty material that's left behind. There is a better way of producing the syngas in the first place, and that is using a technique called underground coal gasification, which means, you don't even have to worry about mining the coal in the first place, basically using a similar process from the oil industry, where you drill two wells. In the first well, you force down the oxygen or the hot air and steam that you're going to use to produce the syngas and in the second bore head, you basically let the gas that has been produced from the conversion of coal.
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