<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=US-ASCII">
<TITLE>Message</TITLE>
<META content="MSHTML 6.00.2800.1170" name=GENERATOR></HEAD>
<BODY>
<DIV><SPAN class=707275800-09072003><FONT face=Arial color=#0000ff size=2>This
has been discussed previously in this forum--check the
archives.</FONT></SPAN></DIV>
<DIV><SPAN class=707275800-09072003><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=707275800-09072003><FONT face=Arial color=#0000ff size=2>I
don't know of any published data off the top of my head, but in several cases
when I was at Amgen we saw dimers and/or higher aggregates in His-tagged
proteins that did not exist for the same protein without the His tag. We also
had cases where the functional properties were significantly altered by the tag.
Hence the use of His tags was largely abandoned there (I don't
know whether that is still true).</FONT></SPAN></DIV>
<DIV><SPAN class=707275800-09072003><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=707275800-09072003><FONT face=Arial color=#0000ff size=2>John
Philo</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><FONT
face=Tahoma size=2>-----Original Message-----<BR><B>From:</B>
rasmb-admin@rasmb-email.bbri.org [mailto:rasmb-admin@rasmb-email.bbri.org]
<B>On Behalf Of </B>John Rodgers<BR><B>Sent:</B> Tuesday, July 08, 2003 3:11
PM<BR><B>To:</B> 'RASMB@rasmb-email.bbri.org'<BR><B>Subject:</B> [RASMB] His
tagged proteins<BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2>
<DIV><SPAN class=112312921-08072003><FONT face=Arial size=2>I can imagine
problems with performing ultracentrifugation experiments with His tagged
proteins. It seems that this was also mentioned in the recent
workshop. A set of equilibrium runs were made before the workshop
with the more abundant and available His tagged protein provided by the
researcher. With regard to the protein, SEC static light
scattering experiments were performed on both native extracted proteins and
His tagged protein with consistent results (dimer-?tetramer in rapid
equilibrim.). The researcher makes the argument
that the His tags are of no significant consequence, but is open
to doing the extra work if a good case can be made for doing
so. Experience, advice and references
appreciated. </FONT></SPAN></DIV>
<DIV><SPAN class=112312921-08072003><FONT face=Arial
size=2>Thanks,</FONT></SPAN></DIV>
<DIV><SPAN class=112312921-08072003><FONT face=Arial
size=2>John Rodgers </FONT></SPAN></DIV></FONT></DIV></BLOCKQUOTE></BODY></HTML>