Source code:
@Grab(group='org.openscience.cdk', module='cdk-bundle', version='2.9')
import org.openscience.cdk.tools.*;
crambin = ProteinBuilderTool.createProtein(
"TTCCPSIVARSNFNVCRLPGTPEA" +
"ICATYTGCIIIPGATCPGDYAN"
);
println "Crambin has " + crambin.atomCount +
" atoms."
Output:
Crambin has 327 atoms.