[Chimera-users] [chimera-users]torsional angle

[吴超]

Hi, folks!
I have a problem about the measurement of torsional angle.
In the chimera users' guide about the command angle, as follows, it says
that if I select the atoms simultaneously, the order information will get
lost.
How can I keep the order information since I need it to calculate the angle
I want exactly?
For example, in the following command I originally want to calculate the
n-ca-c-n(182) dihedral,
angle :181.a at n,ca,c:182.a at n
but in fact  what chimera gave me was may be c-ca-n-n(182).

I want to calculate a lot of diheral information so I can not click one by
one in the gui mode, I wonder is there any way  that I can get what I want .
Thanks!


Usage:
*angle* *atom1 atom2 atom3* [ *atom4* ]

*Angle* reports the bond angle for three
specified<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/midas/atom_spec.html#basic>atoms
or the dihedral angle for four
specified<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/midas/atom_spec.html#basic>atoms.
The order of specification is important, but atoms need not be
connected. The angle value in degrees is reported in the status
line<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/chimerawindow.html#statusline>and
*Reply Log*<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/reply.html>.


The atoms can be specified collectively using the word *selected*, *sel*, or
*picked* if the current
selection<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/selection.html>contains
only the three or four atoms of interest; the order in which the
atoms were selected<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/selection.html>(most
likely
picked<http://www.cgl.ucsf.edu/chimera/1.2199/docs/UsersGuide/selection.html#pickselect>)
is used. When order information is lacking (for example, the atoms were
selected simultaneously), the angle actually measured may not be the one
intended.

There are no automatic updates if the angle changes. A new command must be
issued to measure the changed angle.


-- 
Chao Wu

Currently:
National Institute of Biological Sciences, Beijing
Huang Niu's Lab
http://www.nibs.ac.cn/
Tel: 80726688-8572
Address: Beijing ZhongGuanCun Life Science Park, NO.7 Science Park East
Road, NIBS B427
Postcode: 102206



Life Science Honors Program, China Agricultural University
PO.1055, NO.2 YuanMingYuan west road, Beingjing, 100094
P.R. China
Tel: 86-10-62812484
E-mail: lynnwuchao at gmail.com
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