Published on 05/22/2008

On the face of it, cell biology is booming. Advances in laser optics and multi-photon
techniques are producing ever brighter and sharper pictures of cells, even live ones.
Fluorescent labels make it possible to find out which regions of the genome are
transcribed when; and to track any and every protein in action within the cell.

Strong Medicine for Cell Biology

Molecular malaise in cell biology

On the face of it, cell biology is booming. Advances in laser optics and multi-photon
techniques are producing ever brighter and sharper pictures of cells, even live ones.
Fluorescent labels make it possible to find out which regions of the genome are
transcribed when; and to track any and every protein in action within the cell.
These images are living chronicle of the astonishing diversity of molecular species that
the cell uses in ‘signal transduction’ and downstream processes; the multitude of genes
and non-gene regions of the genome transcribed, the coding messages translated into
protein and transported to the organelles to transform material and energy, to remodel
the cell’s cytoskeleton, to power arrays of molecular motors, not to mention the
battalions of molecular pumps in the cell membrane that must be energized to keep out
unwanted ions and metabolites, the receptors and gates that must be flipped open to let
the nutrients in through special ‘channels’ and to discharge secretions and wastes to the
outside. And all that molecular ‘hardware’ the cell churns up and replaces with unseemly
haste and extravagance as it goes about its business of living.

It simply defies the imagination to figure out how the cell can keep changing shape and
substance yet maintain its unmistakable identity, or else, even more mysteriously,
manage to switch identity to become a different kind of cell. And above all, no matter
what it does, a cell never loses its sense of being an organising, organized whole.
There is a dearth of new ideas that can lift cell biology out of the pervasive molecular
malaise that has infected all of the life sciences to varying degrees in this post-genomics
era: a proliferation of molecular hardware and data, with no modicum of general
understanding on the horizon.

Strong Medicine Needed
Strong medicine is needed; and I have no hesitation in recommending Gilbert Ling’s
latest book. But, like any strong medicine, it is not for the faint-hearted. I only took it
after plenty of encouragement, which is what I hope to pass on to you.
I met Ling for the first time at the prestigious Gordon Research Conference on Interfacial
Water in Cell Biology in Mount Holyoke (Bradley, Massachusetts, USA) in June 2004. He
gave one of the two keynote lectures the first evening, and speaker after speaker
referred to him throughout the week. He was the undisputed hero of the day. It was his
moment of triumph after half a century of relative obscurity. Everyone, including me,
cheered silently for him, and wished him well with all our heart, as though our own
destiny and repute depended on it.

Ling was the hero among a select bunch of fiercely independent and original scientists in
the true sense of the word, motivated by the quest for knowledge of nature above all
else, setting aside personal prestige, politics, worldly success; often at great personal
sacrifice and hardship. Many of the scientists, like Gilbert Ling, have not been afraid to
ask big questions, such as posed by the celebrated quantum physicist Erwin Schrödinger
sixty years ago: "What is life?" It is indeed a mistake to call such scientists ‘mavericks’
and ‘dissenters’, because there is nothing arbitrary about their refusal to accept the
conventional theory that’s riddled with holes and falsehoods; and no coincidence that
they are converging on a more accurate view of what life is.

Ling’s thesis is so important, and so original, that his books should have been read and
understood by everyone at least ten, if not twenty years ago. Sadly, to answer the big
question he is after, or to recognize the answer, requires an understanding of both
physical and biological sciences to a degree that’s beyond most scientists. I know,
because I had tried to read an earlier book of his 20 years ago, before I was quite ready,
and failed almost completely to comprehend it.

This time round, I was determined to discover for myself what it was that had inspired
so many other scientists at the Gordon Conference; and I was thrilled to get an
autographed copy of the latest book from the author himself.

Yet, I had to put the book down five times before finishing it some three months after I
began. Ling has made even his latest book unnecessarily difficult by reproducing
innumerable graphs from his scientific papers, often shrunk down to the point of
illegibility and heavily annotated with small print besides.

The subtitle "The Hidden History of a Fundamental Revolution in Biology" may explain
why Ling has gone to such lengths to document his own work and the contribution of
others with abundant notes and references (557 in all), which also chopped up the text
and spoiled the flow. My advice therefore is to get on with the text, ignoring both the
graphs and notes, only checking them if you feel you must. You will be rewarded
towards the end, as I was.

Debunking the Membrane of Cell Biology

Debunking the Membrane of Cell Biology
In case you are wondering about Ling’s credentials, he and Chinese physicist C.N. Yang
were co-winners of the Chinese national Boxer fellowship that enabled them both to go
to study in the United States. Yang won the Nobel Prize in Physics in 1957, while Ling
soon found himself at odds with the most fundamental theory in cell biology: that the
cell membrane is what keeps the cell intact, by pumping sodium out in exchange for
potassium – which is why the cell has a high concentration of potassium and low
concentration of sodium, precisely the opposite of the fluid outside - and acting as gatekeeper
for glucose and other metabolites, not to mention numerous receptors in the
membrane that are involved in ‘signal transduction’.

Armed with a thorough knowledge of physical chemistry and statistical mechanics, Ling
proceeded to debunk the conventional membrane theory with meticulous experiments,
based on which he developed several theories that fit the observations much better than
the cell membrane theory.

For example, cut muscle cells with big holes in their cell membrane nevertheless
excluded sodium in favour of potassium; furthermore, the cell would need up to 30 times
the ATP it has just to pump out the sodium, leaving nothing for other activities.
Ling’s theories explain the most basic biology of the cell in terms of the physicochemical
state of the protoplasm, the matrix of the living cell. I shall try to sketch the bare
outlines to help orientate readers who will find much, much more in the book itself.
Cell water is organised in multiple layers on an extended protein matrix
The first idea to grasp is that the 70% or so by weight of water associated with the cell –
cell water – is not like water in bulk. Instead, the water molecules are aligned in
ordered layers over a matrix of extended proteins in the ‘protoplasm’ (see Fig. 1).
Figure one. The multiple layers of water molecules aligned over a hydrophilic
surface.

Most people nowadays accept that water molecules immediately next to the hydrophilic
(water loving) surface of proteins are ‘bound’ in some way to the surface, so their
motion is much more restricted than it would be in bulk water, but few believe this
applies to more than one to several layers of water molecules. Ling, however, believes
that practically all the cell water is restricted in motion and arranged in ‘polarized
multilayers.

This organised water has unusual properties, among which, its ability to partially exclude
molecules and ions with large hydration shells, which include the sodium ion, Na+. That
is essentially why the cytoplasm, even without its cell membrane will bind the smaller
potassium ion, K+ in preference to Na+, and the latter need not be pumped out of the
cell by an energy consuming mechanism.

In fact, the bulk of potassium does not exist in free solution in the cytoplasmic matrix. It
is associated with fixed negative charges on the carboxylic acid side chains of the
proteins. That is the earliest of Ling’s theories, which explains why K+ is not freely
diffusible even in a muscle cell that lacks an intact cell membrane, and externally applied
Na+ is still excluded from the cell.

In an astonishing, apparent confirmation of Ling’s ‘polarized multilayer’s or PM
hypothesis, Gerald Pollack and colleagues in Washington University, Seattle, USA, used a
suspension of 0.5 to 2 micron diameter microspheres that can be seen under the
microscope, and showed up massive ‘exclusion zones’ clear of all or almost all
microspheres extending millions of layers of water molecules from the hydrophilic
surfaces of gels. Perhaps other explanations are possible, but they are not yet
convincing. Pollack was inspired by Ling to write a highly readable book that I have
reviewed previously.

A confirmation of Ling’s fixed charge hypothesis – that K+ is associated with carboxylic
acid side chains predominantly in the myosin–rich bands in muscle – came from the
work of Ludwig Edelmann of Saarland University in Germany, who was also at the
Gordon Conference (see "What is the cell really like?" this issue).

The electronic cell

The electronic cell
But still, a major difficulty for conventional biochemists is that the proteins they know
are never extended in solution, but folded up, almost always, in globular conformation
(see "The importance of cell water", this issue for a different, but possibly
complementary view on cell water); and there is no evidence whatsoever that when such
isolated proteins are in solution, they preferentially bind K+ over Na+.
Ling’s answer is that purified isolated proteins are not at all what they are like within the
cell. Instead, within the cell, most, if not all proteins are extended so that the peptide
bonds along their polypeptide chains are free to interact with the multiple layers of
polarized water molecules, and their carboxylic side chains similarly are free to bind
preferentially K+ over Na+. One reason may be the ubiquitous presence of ATP in the
living cell.

Now comes perhaps Ling’s most original idea, and it makes a lot of sense. ATP –
adenosine triphosphate – is the universal intermediate in all energy transformation
processes, be it muscle contraction, protein synthesis, DNA synthesis, transport, etc. It
was once erroneously regarded as the ‘high energy’ intermediate, on account of its ‘high
energy’ phosphate bonds, which turned out not to be the case. Living protoplasm is full
of ATP, which is bound to proteins at certain ‘cardinal sites’, according to Ling. These
ATP-bound sites then induce changes in the electron density, ultimately of the entire
polypeptide chain, including the side chains.

In the absence of ATP, proteins do tend to adopt secondary structures - alpha helix, or a
beta pleated sheet - due to hydrogen bonding between peptide bonds in the same chain,
which gives them a folded up conformation where they don’t interact maximally with
water. However, when ATP is bound to the cardinal site, it tends to withdraw electrons
away from the protein chain, thereby inducing the hydrogen bonds to open up, unfolding
the chain and enabling it to interact with water. This, Ling says, is the ‘resting’ living
state of the protoplasm, a low-entropy state that’s highly organised, possessing what
Schrödinger referred to as ‘negative entropy’ .

Figure 2. Phase transition of protein on binding or releasing ATP.
It may be a misnomer to call the ATP-bound state of the protoplasm a ‘resting state’, as
it is also full of ‘stored energy’ ready to be released when ATP is hydrolysed to ADP. It so
happens that ADP has a much lower tendency to bind to protein, so it comes off the
cardinal site, and the protein naturally reverts to its folded state, an abrupt mechanical
process that releases a lot of energy. It is a thermodynamically downhill or entropydriven
process because it produces disorder among the bound water molecules.
There could be other sites that bind molecules or ligands that have electron-donating
tendency, in which case, an extended protein chain will abruptly adopt the folded up
conformation, and at the same time, lose its ability to selectively bind K+, or even
reverse its preference for binding Na+ over K+. The increase in electron density of the
side-chain carboxylic groups favours the formation of ionic bonds, providing sufficiently
strong attraction for the electropositive Na+ for it to give up its hydration shell.
No elaborate pumps or gates are needed to account for the high concentration of
potassium and low concentration of sodium inside the cell, opposite to the situation in
the extracellular medium. This is a plausible, testable hypothesis, although no one has
yet put it to the test. Ling himself has lost his laboratory facilities at that point.
According to Ling, the abrupt transitions of state are what powers living activities. The
living cell is an exquisite "electronic machine", where everything is done with the
greatest of ease and the least bother, depending on the electron density in specific
protein chains.

Cell membrane and potential membrane demystified
According to Ling, cell membranes do exist, but they are not the barriers to diffusion into
and out of the cell, which, for far too long, has been regarded little more than a ‘bag of
enzymes’ in free solution that would instantly disintegrate were the membrane to
disappear. Rather, the cell membrane is more like the skin of an apple which itself
constitutes a phase similar to the bulk phase it encloses: the major constituents of
membranes are also proteins that behave in a similar way as proteins in the cytoplasm.
They too, preferentially bind K+ over Na+ in the resting state. Membrane potentials are
local surface potentials, while action potentials simply reflect the changes of state that
involves a release of bound water and the temporary exchange of Na+ for K+ bound to
the carboxylic acid groups in the protein side chains.

The living state is flexible and liquid crystalline
The picture of what Ling has referred to as the ‘resting’ living state with ATP and lots of
associated water is very much like the liquid crystalline state that I and my colleagues
have discovered in cells and organisms, which is another reason why I believe Ling may
be largely correct. The living state – as opposed to the state of death in which ATP is
exhausted, and rigor mortis sets in - is maximally hydrated by polarized layers of bound
water and hence flexible and full of energy. This idea of the truly living cell is beautifully
brought to life in the inspired portraits produced by Ludwig Edelmann.

Source
http://www.i-sis.org.uk/SMFCB.php