Dear all,

I am dealing with a EM map which is a double helical filament and composed of two protein chains winding each other. Each of the two chains is composed of multiple same protein subunits. Now I am trying to color one chain of the map with one color, and the other chain with another color. How should I do that?

Besides, it is known that multiple such double helixes can constitute a longer helix by a head-to-tail way.  I can open several helixes in chimera, but how to concatenate they correctly into a long helix?