Received: by alpheratz.cpm.aca.mmu.ac.uk id TAA24502 (8.6.9/5.3[ref firstname.lastname@example.org] for cpm.aca.mmu.ac.uk from email@example.com); Tue, 21 Aug 2001 19:48:10 +0100 Message-ID: <005001c12a71$98835760$eb25f4d8@teddace> From: "Dace" <firstname.lastname@example.org> To: <email@example.com> References: <3B807B87.22754.C003D0@localhost> Subject: Re: Multiple-minimum Date: Tue, 21 Aug 2001 11:46:26 -0700 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Sender: firstname.lastname@example.org Precedence: bulk Reply-To: email@example.com
> 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
> 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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