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On 21 Aug 2001, at 11:46, Dace wrote:
> joedees wrote:
> > Dace wrote:
> > > According to morphic theory, the same protein configuration should
> > > occur even when composed of entirely different sequences of amino
> > > acids. This is exactly what happens. Among the serine proteases,
> > > for instance, only 40% of the positions in the polypeptide chains
> > > are occupied by the same amino acids. Yet they are strikingly
> > > similar, with most of the twists and turns being identical. Same
> > > thing with the hemoglobins. They all have virtually the same
> > > structure, yet none of them share more than three amino acids out
> > > of the 140 to 150 slots along the chain.
> > >
> > > Sheldrake isn't denying the importance of the chemical properties
> > > of polypeptides. He's merely pointing out that these properties
> > > alone cannot account for protein-folding.
> > >
> > When the amino acids are different yet the combinatory
> > configurations formed by their bindings are similar, this would be
> > expected to happen.
> Why should different amino acids have the same combinatory
> configurations? This denies the importance of chemical properties in
> the folding process.
No, different protein strings may be tipped with the same amino
acids, where the ends are the same but that which is between
them is different.
> > And as far as only three out of 150, this is
> > exceedingly strange, as there are only 22 amino acids.
> Hemoglobins have approximately 150 slots for amino acids, not 150
> different amino acids.
But not 150 distinctly diffeerent lock-and-key configurations.
> Chris wrote:
> > My entire Ph.D. was on neutral evolution - there are many peptides
> > that fold to the same protein (same with RNA secondary structures).
> > This works both ways too - striking similar sequences can do
> > radically different jobs when folded and in situ. However none of
> > this remotely challenges the existing orthodoxy about protein
> > folding, or evolution.
> How can a theory which relies on thermodynamics account for virtually
> the same sequences of amino acids folding in radically different ways
> or radically different polypeptides folding in roughly identical ways?
It relies on much more than thermodynamics; organic chemistry is
several levels above physics, and each level produces its own
synergistic and emergent laws.
> > If MR were true, then why is such neutral drift allowed?
> MR is not deterministic. It's probabilistic. Sometimes things don't
> follow probability. Once a protein has drifted into a different form,
> then that form will be stabilized by morphic resonance.
Howzabout an explanation that'll actually work? In chaos and
complexity theory, you have what are called fitness landscapes,
and there are minimum-energy points within such landscapes
called strange attractors. Processes seeking equilibrium will
naturally gravitate to such attractors, because they are where their
products will assume the most stable configurations given their
> This was distributed via the memetics list associated with the
> Journal of Memetics - Evolutionary Models of Information Transmission
> For information about the journal and the list (e.g. unsubscribing)
> see: http://www.cpm.mmu.ac.uk/jom-emit
This was distributed via the memetics list associated with the
Journal of Memetics - Evolutionary Models of Information Transmission
For information about the journal and the list (e.g. unsubscribing)
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