f.write('BOXX='+str(instance.boxx)+' BOXY='+str(instance.boxy)+
' BOXZ='+str(instance.boxz)+cntrl_saxs +'\n')
f.write(w+'\n')
for i in range(0,len(seq),80):
f.write(seq[i:i+80]+'\n')
f.write(write_ssbond(instance.ssbond))
f.write('BOXX='+str(instance.boxx)+' BOXY='+str(instance.boxy)+
' BOXZ='+str(instance.boxz)+cntrl_saxs +'\n')
f.write(w+'\n')
for i in range(0,len(seq),80):
f.write(seq[i:i+80]+'\n')
f.write(write_ssbond(instance.ssbond))