Gly phi constraints
johnk at spasm.niddk.nih.gov
Wed Nov 15 16:54:48 EST 1995
In article <48d4q1$36b at news.ox.ac.uk>, Kristy Downing <kristy at bioch.ox.ac.uk> writes:
|> Dear All,
|> I have extracted coupling constants corresponding to Gly HA1-HN and HA2-HN from
|> a HNHA experiment, and I would now like to use this information to derive
|> backbone phi constraints. I have two questions:
|> (i) How do the couplings relate to the phi angle? For example, if one HA-HN
|> coupling constant is 4.0 Hz and the other is 7.4 Hz, what equation do I use to
|> derive phi? (If anyone knows of a reference, I would be very grateful!)
I just talked to Andy Wang, one of Ad Bax's postdocs, about this.
The Karplus curve that Vuister and Bax published (as well as a re-worked
version that Andy and Ad have in-press) does not work well for gly.
I wouldn't try to include phi restraints from gly 3J HnHa couplings.
|> (ii) Are glycine phi constraints encoded the same way in X-PLOR as other
|> backbone torsion angle constraints, i.e., using the atoms of C(i-1), N, CA, and
Yes, although better ways of dealing with this information,
such as my direct refinement techniques, have been developed too.
| |/ /
-- /\ // /--
|| || / /||
|| || / / ||
|| ||/ / ||
John Kuszewski || |/ /| ||
johnk at spasm.niddk.nih.gov || / /|| ||
\/ / / || \/
that's MISTER protein G to you! |/__/| |
"Biophysics has driven me to an attitude of apocalyptic doom"
More information about the X-plor