diff --git a/ippisite/ippidb/models.py b/ippisite/ippidb/models.py
index daa6ca0fce35dcaba40ae752be11e1cfdb5213f9..bc8e5b0b1b03c2fdb4f9128ca07c45442e959e51 100644
--- a/ippisite/ippidb/models.py
+++ b/ippisite/ippidb/models.py
@@ -72,7 +72,6 @@ class Domain(models.Model):
     domainfamily = models.CharField('Domain family', max_length=25)  #TODO: what is this field? check database contents
 
 class ProteinDomainComplex(models.Model):
-    complex_id = models.IntegerField('Complex identifier')
     protein_id = models.ForeignKey('Protein')
     domain_id = models.ForeignKey('Domain')
     ppc_copy_nb = models.IntegerField('Number of copies of the protein in the complex')
@@ -101,7 +100,7 @@ class Symmetry(models.Model):
 class Ppi(models.Model):
     ppi_id = models.IntegerField('PPI identifier')
     complex_id = models.ForeignKey(ProteinDomainComplex)
-    cc_nb = models.IntegerField('Number of copies of the complex in the PPI')
+    cc_nb = models.IntegerField('Number of copies of the complex in the PPI', default=1)
     pdb_id = models.CharField('PDB ID', max_length=4)
     symmetry_id = models.ForeignKey(Symmetry)
 
@@ -169,7 +168,7 @@ class Compound(models.Model):
     chemspider_id = models.CharField('Chemspider ID', unique=True, max_length=10, blank=True, null=True)  
     chembl_id = models.CharField('Chembl ID', unique=True, max_length=30, blank=True, null=True)  
     iupac_name = models.CharField('IUPAC name', unique=True, max_length=255, blank=True, null=True)  
-    mddr_compound_id = models.ForeignKey('MDDRCompoundImport', 'MDDR compound', unique=True, blank=True, null=True)  
+    mddr_compound_id = models.ForeignKey('MDDRCompoundImport', blank=True, null=True)  
 
 
 class MDDRCompoundImport(models.Model):