'Lego' Approach Thwarts Anthrax Toxin 78
NewScientist is reporting that scientists have discovered complex nanoscale structures that have successfully protected rats from anthrax. From the article: "The technique relies on using tiny 'peptide' molecules, stuck onto one large molecule, which bind to toxins and prevent them from causing damage. They do this in much the same way that two Lego bricks might fit together - with several studs from the binding molecule slotting into, and so blocking, the sites on a toxin molecule which are needed to cause damage."
Re:Ho Hum... (Score:2, Interesting)
It is interesting that they're doing it with nano-tech though. What are the odds on becoming Grey Goo [wikipedia.org]? (Well, okay, none because it's not assemblers/disassemblers, but I haven't read anything that makes me real eager to snort a bunch of nano-tube structures either)
Surprise, surprise... (Score:5, Interesting)
That's called an antibody [wikipedia.org].
Re:Ho Hum... (Score:3, Interesting)
The basic premise of the research is very simple. Create an immobilized synthetic binding site for the toxin so you can essentially titrate it out of solution so it is no longer free to do its toxic thing.
Good week for antrax (Score:3, Interesting)
Now, along with the anthrax killer protien [sciencedaily.com], we are making progress, indeed.
Whats more, this protien looks to be anti-resistant too.
The Article with all the crap filtered out: (Score:3, Interesting)
In their control group, 8 out of 9 rats given the toxin (not the actual anthrax bacteria, though) died. In the test group, only 1 of 9 rats given the toxin plus 500 mg of the protein-embedded liposomes died. Since the protein only targets the toxin, the treatment would have to be used in conjunction with antibiotics to kill the bacteria. There is no mention in the article whether the toxins and liposomes are flushed out of the body or broken down, but the end result is that the toxins can't bind to whatever it is they normally do to cause trouble.
Liposome probably isn't a familiar term, so look up liposome [wikipedia.org] or cell membrane [wikipedia.org] (includes drawing of embedded proteins) if you want to get a better understanding. Wikipedia has a decent article on anthrax, but I googled and found a much better write up [textbookof...iology.net] from the University of Wisconsin that might help you get a good "big picture" look at what goes on.
From my reading it looks like there are multiple toxins. One causes septic shock through a method that is apparently not yet fully understood. It bonds to a protein in the cell membrane (just like the proteins in the liposomes), and interferes with cellular signalling. Fascinatingly, two other toxins actually cause ATP depletion and swelling in phagocytes (a particular type of cell in the immune system) so that they aren't able to engulf the anthrax bacteria and break them down. It's like a biological counter-countermeasure. Not karma whoring...I just thought after I'd looked up all that information some other people would be interested, too. All this reminds me why I enjoyed biology so much back in high school.
Re:'Lego' Approach - new'...?? (Score:3, Interesting)
Many drugs work by binding to a target protein and inhibiting its activity in this way. However, there are several ways to achieve this. The conventional form of drug is a "small molecule", created by organic chemistry. These are called small because they are much smaller (and less complex) than proteins -- say more than a factor 10 smaller.
Small molecules can have enormous advantages: They are relatively easy to manufacture and to store, and if they are stable enough and well absorbed, they can be taken orally. If you want something simple and cheap for large-scale use, a small molecule is the way to go. However, the downside is that they are very complex and expensive to develop.
The other big category is that of the "biologicals", which includes proteins and peptides -- a peptide is essentially a small fragment of a protein, but still bigger than a small molecule. Antibodies are a category of proteins; in the case of antibodies, development is relatively easy because the body produces them naturally. There is also the possibility of taking a protein's natural binding partner, and then synthesising this on a large scale to outcompete the natural binding partner. The general expectation is that biogicals will be easier to develop than small molecules and for many diseases, will be the first form of treatment available.
The typical disadvantages of biologicals are that they need to be stored in a freezer, must be injected rather than swallowed or inhaled, and are expensive to manufacture. This usually restricts their use to relatively small numbers of patients, in hospital environments or receiving intense attention from their physicians. (Insulin is a well-known exception, however.)
Some people believe that small molecules are fundamentally unable to block certain interactions. The reasoning is that that something small can only attach efficiently to a target site if the available forces on that site are large enough, i.e. if there is a so-called "pocket" to fit the molecule in. While biologicals, because they are bigger, can bind over a wider area, so can be effective even if smaller forces are involved.
In this case, the scientists took peptides, which are relatively small, but instead of combining them into an actual protein (which would have been very complex and expensive) they grouped them together on the surface of a liposome, which essentially is a tiny droplet of fat. And the observation is that indeed, the interaction of the multiple peptides with the target still adds up, giving the liposome a much stronger binding to its target than the individual liposomes.
This creates numerous interesting possibilities. This might work with small molecules as well as peptides, for example; or you might even combine the two in a single treatment.