Syntax:  backbone {<boolean>}
         backbone <value>

The RasMol backbone command permits the representation of a polypeptide backbone as a series of bonds connecting the adjacent alpha carbons of each amino acid in a chain. The display of these backbone `bonds' is turned on and off by the command paramater the same as the wireframe command. The command backbone off turns off the selected `bonds', and backbone on or with a number turns them on. The number can be used to specify the cylinder radius of the representation in either angstrom or rasmol units. A parameter value of 500 (2.0 angstroms) or above results in a "Parameter value too large" error. Backbone objects may be coloured using the RasMol colour backbone command.

The reserved work backbone is also used as a predefined set and as a parameter to the set hbond and set ssbond commands. The RasMol command trace is synonymous with the command backbone.