"TOPO_DOM 1 ...
^^

##</code><code>##

> perl -de0
...
  DB<21> $string="TOPO_DOM 1; /note=Cytoplasmic; /evidence=ECO:0000269|PubMed:24744376; TOPO_DOM 25..74; /note=Extracellular;..."

  DB<22> x split /TOPO_DOM/, $string
0  ''
1  ' 1; /note=Cytoplasmic; /evidence=ECO:0000269|PubMed:24744376; '
2  ' 25..74; /note=Extracellular;...'
  DB<23>