Hi
I've been having a play with this to see what behaviour I get and
uncovered some issues. One of which causes spin system merging without
a warning.
On 16 Feb 2006, at 13:52, Tim Stevens wrote:
> The idea is that you should assign the HNCA and HNcoCA matching peaks
> to
> the same carbon resonance (i.e. in the same spin system).
OK. This makes sense. So the i-1 peak in the HNcoCA would have an
assignment like e.g.
{77}[101] {77}[102] {34} [200] where the dimensions are Hn, N, CA
And the preceding spin system {34} i peak is assigned e.g:
{34}[55] {34}[56] {34}[200] dimensions again Hn, N, CA
If I now assign spin system 77 to an amino acid N then the assignment
is propagated to all peaks in that spin system as expected. However the
assignment of spin system 34 as the previous amino acid (N-1) does not
happen. Again this is expected as I have not used set sequential spin
systems. If I then do this all the assignments of spin system 34 are
changed to N-1 as they should be.
All OK so far.
If however, I use "set sequential spin system" before any residue
assignment the (i-1) spin system number changes. The previous number
(34 in my example) disappears from the edit spin system table and is
replaced by a new spin system. The resonance numbers remain the same.
This makes keeping track of spin systems quite problematic. Is this the
intended behaviour? As I understood it the sequential order of spin
systems is independent of their numbering so analysis should have no
problem with spin system 34 preceding 77. I want to make sure there
isn't some other problem in the way spin systems have been assigned
(initialise HSQC to get spin system numbers, then assign3Dfrom2Droot to
propagate these to the triple resonance experiments).
Now the more serious problem. Using set sequential spin systems wrongly
with 0 0 -1 and 0 0 +1 will cause two spin systems that were
independently numbered to have the same number i.e they have been
merged into the same spin system without warning. This is as would be
expected based on the sequential connectivity information you have
entered. This is really dangerous as in all other cases merging spin
systems gives you a warning and could take a long time to undo if done
inadvertently.
Hope all that makes sense, I just wanted to clarify the way connected
strips without residue specific assignments should be done.
Huw
--
Huw Jenkins
School of Chemistry
University of Edinburgh
West Mains Road
Edinburgh, EH9 3JJ
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