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Mitra,<br>
It is also possible to get a slightly low f/fo (sometimes less than
1.0) if there is a small amount of unaccounted for self-association
going on.<br>
Walter<br>
<br>
John Philo wrote:
<blockquote cite="mid:E6BAEBCA1EB8441D9EFB44470736FA4F@79B7XD1"
type="cite">
<title>Re: [RASMB] Hb tetramer</title>
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<div dir="ltr" align="left"><font color="#0000ff" face="Arial"
size="2"><span class="878221716-04022009">Mitra,</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" face="Arial"
size="2"><span class="878221716-04022009"></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" face="Arial"
size="2"><span class="878221716-04022009">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).</span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="878221716-04022009"></span></font> </div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="878221716-04022009">John</span></font></div>
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<hr tabindex="-1"><font face="Tahoma" size="2"><b>From:</b>
<a class="moz-txt-link-abbreviated" href="mailto:rasmb-bounces@rasmb.bbri.org">rasmb-bounces@rasmb.bbri.org</a> [<a class="moz-txt-link-freetext" href="mailto:rasmb-bounces@rasmb.bbri.org">mailto:rasmb-bounces@rasmb.bbri.org</a>] <b>On
Behalf Of </b>Arthur Rowe<br>
<b>Sent:</b> Wednesday, February 04, 2009 6:45 AM<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:mitrana@mail.utexas.edu">mitrana@mail.utexas.edu</a>; <a class="moz-txt-link-abbreviated" href="mailto:rasmb@server1.bbri.org">rasmb@server1.bbri.org</a><br>
<b>Subject:</b> Re: [RASMB] Hb tetramer<br>
</font><br>
</div>
<blockquote>Hi Mitra<br>
<br>
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. <br>
<br>
Regards<br>
<br>
Arthur<br>
<br>
</blockquote>
<br>
<blockquote><tt>Hello All<br>
Two questions, related ones -<br>
<br>
1. Is a S20,w value of 5.01 too high for a DEOXY Hb tetramer of 67180 <br>
Da MW? This gives a f/f0 of around 1.08. Just a reminder that deoxy Hb <br>
tetramer does not dissociate to a dimer much (dissociation constant ~ <br>
10^-11 M).<br>
<br>
2. can such an anomaly occur due to Hb interactions with the <br>
components of the buffer - in this case 2 mM of Inositol <br>
hexakisphosphate (IHP)?<br>
<br>
Glad to hear any comments and/or references to papers.<br>
<br>
Mitra<br>
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