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<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=889325315-08052014>Tom, I don't think your recollection of a constant
value of ~2.7 S is correct in general for protein rods. For very long rods (high
length to diameter ratios) the sedimentation coefficient does become independent
of length, but the sedimentation coefficient value will be determined by the
buoyant mass per unit length, which of course depends strongly on the
rod diameter. </SPAN></FONT></DIV>
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class=889325315-08052014></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=889325315-08052014>I did once run velocity on some carbon nanotubes,
but due to this very weak length dependence it provides very poor separation by
length. </SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=889325315-08052014></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=889325315-08052014>SEDNTERP will of course calculate length/diameter
ratios for shorter rods (cylinders) out to ratios of about 10.
</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=889325315-08052014></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=889325315-08052014>John</SPAN></FONT></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> rasmb-bounces@list.rasmb.org
[mailto:rasmb-bounces@list.rasmb.org] <B>On Behalf Of </B>Laue,
Thomas<BR><B>Sent:</B> Thursday, May 08, 2014 8:42 AM<BR><B>To:</B> RASMB List
?[rasmb@list.rasmb.org]?<BR><B>Subject:</B> [RASMB] Sedimentation of
rods<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV
style="FONT-SIZE: 12pt; FONT-FAMILY: Times New Roman; COLOR: #000000; DIRECTION: ltr">Hi
all-<BR>We are looking at a protein that forms rods. I have little background on
systems like this, and am looking for some guidance. In particular, my
recollection is that for long rods, as the rod length increases, the s collapses
back to a constant ~2.7 s. <BR>Any wisdom will be welcome.<BR>Best
wishes,<BR>Tom<BR></DIV></BODY></HTML>