Biology Reference
In-Depth Information
123
http://www.rcsb.org/pdb/, except possibly those predicted theoretically. The
Cartesian coordinates for non-hydrogen atoms are usually reported.
However, and angles are not available. In this Chapter, how these
angles can be calculated from atomic coordinates will be explained in detail.
UNIT NORMALS TO PLANES
To define a plane, we need to specify its unit normal. For the three planes
shown in Fig. 5-3, and the unit normals can
be calculated from the vectors drawn from to C
-1
, N, C and N
+1
.
Therefore, starting with the atomic coordinates of C
-1
, N, C and N
+1
, we
need to translated the origin of the coordinate system to Then, in the
translated system, the coordinates for C
-1
, N, C and N
+1
specify the vectors
C
-1
,
N, C
and
N
+1
respectively. The unit normals for the three planes are as
follows:
plane
plane
and plane
AND
ANGLES AS ANGLES BETWEEN PLANES
Since the
angle is the angle between planes
and
we
have:
