@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .
@prefix owl:  <http://www.w3.org/2002/07/owl#> .
@prefix prov: <http://www.w3.org/ns/prov#> .
@prefix :     <http://example.com/> .
:digestedProteinSample1
   a prov:Entity;
   prov:wasDerivedFrom :proteinSample;
   prov:qualifiedDerivation [
      a prov:Derivation;
      prov:hadUsage [
         a prov:Usage;
         prov:entity :Trypsin;
        prov:hadRole :treatmentEnzyme;
      ];
   ];
   prov:entity :proteinSample;
.
:proteinSample a prov:Entity .