Re: SciAm: nano and cryonics

From: Robert J. Bradbury (
Date: Fri Aug 17 2001 - 18:05:53 MDT

Hal offered a review of my editorial and made some good counterpoints
and suggestions. I'll only make some minor points in response.

Whitesides said "does not act by using electric current".
If you are aren't going to call the flow of hydrogen ions
an electric current then I think you may be splitting
some mighty thin hairs. He specifically implies that
the decomposition of ATP is involved in the molecular
ratchet that drives the shaft and it isn't.

It would make sense that ATP synthase evolved from the flagellum
rotor since mitochondria are evolved from bacteria, they produce
the same H+ ion gradient that bacteria do and there is a subcomponent
of the flagella proteins that has an ATPase activity. A little bit
of gene shuffling and that evolves into an ATP synthase.

I didn't really want to get into a discussion of the many/fat
fingers problem until I'd read Smalley's article. Yes, I'm aware
of Ralph's work but its also obvious to anyone who has studied
biochemistry. How does catechol-O-methyl transferase transfer
the methyl group from S-adenosylmethionine onto norepinephrine
prodicing normetanephrine if it can't properly "grab" and "position"
those two molecules relative to one another? What about all the
hydrogenases, oxidases, kinases, dehydrogenases, deoxidases,
phosphatases, etc. that allow us to live? The argument just
doesn't make any sense to me (this will be discussed in more
detail in the paper I'm writing so it didn't make sense to include
it in the letter).

I'll take a look at WSOT.html. One problem is I need to finish
the paper that states the argument you object to more clearly
but that comes after the nanopart assembly paper.

I may not have made clear the "medical" connection. It was his
statement "No simple markers on the outside of most cancer cells
flag them as dangerous" that raised my eyebrows. Any medical
person reading the paper would immediately think of Prostate Specific
Antigen and/or a host of other molecules that people are currently
testing for the purpose of targeting drugs or radioactive ligands
to cancer cells. The simple examination of the surface of
cells for the MHC proteins binding a mutated p53 fragment would take
you a long way toward towards a general means to recognize
potentially cancerous cells. (The problem with this is that
some people may have MHC alleles not particularly effective
at displaying mutant p53 fragments, so you have to actually
enter the cell and sequence p53 mRNA molecules looking for errors).
I can discuss that here, but I didn't think it would fly
in a letter to the editors...

When I put the paper up on the web, I'll try to expand it to be
more complete. My critiques are getting really backed up as
I still haven't finished my critique of Vogel's paper in
the NSF's societal impact publication. Arghhhh....

I would say a chemist's knowledge base extends up to the
range of molecules of ~1000 daltons. The range from 150-1000 D
is usually the stomping ground of the biochemists. Really
high molecular weight compounds are the speciality of polymer
chemists. If you want to talk electrical current you should
be talking to a biophysicist or an electrical engineer.
If you want to talk about self-replication you want to talk
to a microbiologist or a computer scientist. None of this
is to say that I think Whitesides is a poor scientist.
His invention of nano-imprint lithography makes him
pretty brilliant in my book. (He won a Foresight prize
for that a few years ago.) I just think he should read
a little more of the literature before he writes about MNT.

One thing Vogel does get right in her NSF paper is that its
going to take a lot of interdisciplinary training to get the
"systems engineers" that Eric points out we *really* need.


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