Re: Multiple-minimum

From: Dace (
Date: Tue Aug 21 2001 - 19:46:26 BST

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    From: "Dace" <>
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    Subject: Re: Multiple-minimum
    Date: Tue, 21 Aug 2001 11:46:26 -0700
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    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.

    > 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.

    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?

    > 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.


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