[RASMB] Hb tetramer

[John Philo]

Mitra,
 
My recollection is that IHP does cause a slight compaction of the structure,
but I agree with Arthur that 1.08 sounds a bit low. I'm wondering whether
that might be because you are not using an accurate vbar value. I wasn't
doing AUC back in the dark ages when I worked on hemoglobin, but I vaguely
recall that the additivity rule for vbar may not work well for heme +
globin. I think you will find the experimental vbar in hemoglobin AUC papers
by Stuart J. Edelstein (? '60s-'70s).
 
John

  _____  

From: rasmb-bounces at rasmb.bbri.org [mailto:rasmb-bounces at rasmb.bbri.org] On
Behalf Of Arthur Rowe
Sent: Wednesday, February 04, 2009 6:45 AM
To: mitrana at mail.utexas.edu; rasmb at server1.bbri.org
Subject: Re: [RASMB] Hb tetramer



Hi Mitra

An f/f0 value of 1.08 (±?) is low-ish, but within the ball park range for
'globular' proteins. I don't imagine that 2 mM Inositol would affect the
(properly and fully corrected) s value. 

Regards

Arthur




Hello All
Two questions, related ones -

1. Is a S20,w value of 5.01 too high for a DEOXY Hb tetramer of 67180  
Da MW? This gives a f/f0 of around 1.08. Just a reminder that deoxy Hb  
tetramer does not dissociate to a dimer much (dissociation constant ~  
10^-11 M).

2. can such an anomaly occur due to Hb interactions with the  
components of the buffer - in this case 2 mM of Inositol  
hexakisphosphate (IHP)?

Glad to hear any comments and/or references to papers.

Mitra
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