Hi,
Many thanks to all who replied to my enquiry about the weakest protein-
protein complex crystallised. The idea that crystals themselves are
weak complexes had already crossed my mind and I was glad to hear it
confirmed by others. My impression is that there are no hard and fast
rules,
De : Filip Van Petegem [mailto:[EMAIL PROTECTED]
Envoyé : Monday, June 30, 2008 9:01 PM
À : Philippe DUMAS
Cc : CCP4BB@jiscmail.ac.uk
Objet : Re: [ccp4bb] Weakest protein-protein complex crystallised
Hi,
we've had a similar situation: a protein-peptide complex with a Kd in the
nM range
Hello John,
No, they're not. Crystals were obtained at pH8.0, 200mM NaCl; 10%
PEG4000. Calorimetric experiments were done at pH7.4, 150mM KCl. We found
the interaction to be driven mainly by hydrophobic contacts (mutants of
polar/charged residues have no significant effect on the affinity). I
ed
> > > "contaminants". This is exactly the order of magnitude mentioned by Ed
> > > Pozharski: a single additional H-bond is enough to account for 2
> kcal/mol
> > > ! And apparently this may be enough to win against "biological
> > >
omparable
> > to crystallization in living cell...
> >
> > I hope this story makes sense in the frame of this discussion.
> >
> > Philippe Dumas
> > IBMC-CNRS, UPR9002
> > 15, rue René Descartes 67084 Strasbourg cedex
> > tel: +33 (0)3 88 41 70 02
&
PROTECTED]
>
> -Message d'origine-
> De : CCP4 bulletin board [mailto:[EMAIL PROTECTED] la part de Ed
> Pozharski
> Envoyé : Monday, June 30, 2008 4:50 PM
> À : CCP4BB@JISCMAIL.AC.UK
> Objet : Re: [ccp4bb] Weakest protein-protein complex crystallised
>
>
> T
o:[EMAIL PROTECTED] la part de Ed
Pozharski
Envoyé : Monday, June 30, 2008 4:50 PM
À : CCP4BB@JISCMAIL.AC.UK
Objet : Re: [ccp4bb] Weakest protein-protein complex crystallised
The word "weak" is, of course, relative. Free energy of crystallization
is roughly 1-2 kcal/mole of crystal conta
There are quite a number of structures homodimers and homotetramers in the PDB
where the dissociation constant is known to be in the millimolar range.
For example the dimerizaion of a humainized antibody VHH domain that mimicks a
VH-VL complex (Conrath et al. J. Mol. Biol. (2005) 350, 112125).
The word "weak" is, of course, relative. Free energy of crystallization
is roughly 1-2 kcal/mole of crystal contacts (I think I carried this
number from Sir Blundell's book, but quick look at papers by Peter
Vekilov's group seems to confirm it - am I wrong on this?). I think
that crystal contacts
I hope this isn't too much of a foray into philosophy and semantics,
but can't you argue that the crystals themselves are weak complexes?
And since the energies of crystal contacts are typically very weak, I
would further argue that you should be able to crystallize ANY
complex with an asso
Hi,
Can anyone advise me what is currently the weakest protein-protein
complex yet crystallised? Google searching turned up a paper from the
Tromsø crystallography group (Helland et al. 1999, JMB 287, 923–942)
in which a complex between beta-trypsin and a P1 mutant of BPTI with a
Kd of 68
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