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  From: Geoff=Howlett%BioChem%UNIMELB@muwaye.unimelb.EDU.AU
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  Date: Sun, 1 May 94 8:45:59 +1000 subject...

Re: Simple associating systems (request by Allen Furst)

To the extent this network is focussing on reversible associations it is 
remarkable that there seem to be no standards to compare equipment and 
analytical procedures from different labs.  Greg Ralston suggested beta-
lactoglobulin at low pH as a possibility.

I taliked with Ernesto Freire when he was here and we embarked on a project 
to characterise the association behaviour of an amphipathic peptide as a 
possible standard.  It is ironic that we are currently in a situation where 
we can't even agree whether the peptide is a dimer (calorimetry data) or a 
monomer (centrifuge data).

To be a good standard I would suggest we look at the following criteria:

1.  	Stable and small enough to be characterised be mass spectroscopy.
2.  	Easy to purify and genetically pure.  This would support a bacterial 	
	origin where it is possible to sequence the coding gene.
3.	Of known three dimensional structure and capable of discreet 		
	aggregation. ie specific dimerisation.
4.	Aggregation under conditions which are not strongly temperature or pH 
5.	Published data are available.
6. 	Someone is available to distribute large quantities of the purified 	

While separate criterion might apply for plasmon resonance, spectrocopic and 
microcalorimery data it would be desirable that standards be suitable for 
study using different techniques.

A possibility I have considered is the small RNA binding protein ROP which 
exists as a dimer, has a known 3D structure (a small 4 helix bundle) and has 
recently been described (Biochemistry vol 32 3867-3876). Does anyone know 
have experience with this protein?

There must be other possibilities. Then again - Standards? - what are they?

My 2 cents worth.

Geoff Howlett

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