grated into ERNA-3D relatively recently. ERNA-2D can be understood as a pro-
gram within the program and communicates with the 3D-functions of ERNA-3D
in a very intelligent manner. With ERNA-2D it is now possible to generate Se-
condary Structure Maps of molecules in such a flexible manner never seen be-
fore. Analogous to ERNA-3D, all single strands are also flexible and can be pul-
led in an absolutely dynamic way. Double helices and other structure parts can
be moved around while all connected flexible strands follow the movement.
Moreover the most important feature of ERNA-2D is its ability to create three-
dimensional atomic structures within seconds directly out of the just edited Se-
condary Structure and to communicate with ERNA-3D via interactive selections
done by the user.
A further useful feature of ERNA-2D is its ability to create Secondary Structu-
re Parts directly from a three-dimensional atomic structure. Accordingly, if a 3D-
structure is extracted from a data bank (e.g. PDB), its Secondary Structure can
be generated, if the definitions in the PDB file are correct.
Parts by using a so-called "Selbox", which can be drawn arround any part
of the Secondary Structure.
