diff --git a/ippisite/ippidb/migrations/0025_auto_20171110_1046.py b/ippisite/ippidb/migrations/0025_auto_20171110_1046.py
new file mode 100644
index 0000000000000000000000000000000000000000..a8726087da8c0b36c5b71e72f6f95bdd2dbe1089
--- /dev/null
+++ b/ippisite/ippidb/migrations/0025_auto_20171110_1046.py
@@ -0,0 +1,61 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.4 on 2017-11-10 10:46
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('ippidb', '0024_auto_20170523_2000'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='bibliography',
+            name='in_cellulo',
+            field=models.BooleanField(default=False, verbose_name='in cellulo study'),
+        ),
+        migrations.AlterField(
+            model_name='bibliography',
+            name='in_silico',
+            field=models.BooleanField(default=False, verbose_name='in silico study'),
+        ),
+        migrations.AlterField(
+            model_name='bibliography',
+            name='in_vitro',
+            field=models.BooleanField(default=False, verbose_name='in vitro study'),
+        ),
+        migrations.AlterField(
+            model_name='bibliography',
+            name='in_vivo',
+            field=models.BooleanField(default=False, verbose_name='in vivo study'),
+        ),
+        migrations.AlterField(
+            model_name='bibliography',
+            name='pharmacokinetic',
+            field=models.BooleanField(default=False, verbose_name='pharmacokinetic study'),
+        ),
+        migrations.AlterField(
+            model_name='bibliography',
+            name='source',
+            field=models.CharField(choices=[('PM', 'PubMed ID'), ('PT', 'Patent'), ('DO', 'DOI ID')], default='PM', max_length=2, verbose_name='Bibliographic type'),
+        ),
+        migrations.AlterField(
+            model_name='bibliography',
+            name='xray',
+            field=models.BooleanField(default=False, verbose_name='X-Ray data'),
+        ),
+        migrations.AlterField(
+            model_name='compoundaction',
+            name='activation_mode',
+            field=models.CharField(choices=[('O', 'Orthosteric'), ('A', 'Allosteric'), ('U', 'Unspecified')], max_length=1, verbose_name='Activation mode'),
+        ),
+        migrations.AlterField(
+            model_name='protein',
+            name='organism',
+            field=models.ForeignKey(default='Homo sapiens', on_delete=django.db.models.deletion.CASCADE, to='ippidb.Taxonomy'),
+        ),
+    ]
diff --git a/ippisite/ippidb/migrations/0026_auto_20171110_1426.py b/ippisite/ippidb/migrations/0026_auto_20171110_1426.py
new file mode 100644
index 0000000000000000000000000000000000000000..0dca58c57af03dd6d5061ddcfb8a7b7443cb686c
--- /dev/null
+++ b/ippisite/ippidb/migrations/0026_auto_20171110_1426.py
@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.4 on 2017-11-10 14:26
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('ippidb', '0025_auto_20171110_1046'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='compoundaction',
+            name='pdb_id',
+            field=models.CharField(blank=True, max_length=4, null=True, verbose_name='PDB ID'),
+        ),
+    ]
diff --git a/ippisite/ippidb/models.py b/ippisite/ippidb/models.py
index 232e595e92ef3807ff99b21fa2cabed997f7de95..5e4c3d225e8da27831ddd30b070c7103291ec8f8 100644
--- a/ippisite/ippidb/models.py
+++ b/ippisite/ippidb/models.py
@@ -513,13 +513,14 @@ class CompoundPKResult(models.Model):
 class CompoundAction(models.Model):
     ACTIVATION_MODES = (
         ('O', 'Orthosteric'),
-        ('A', 'Allosteric')
+        ('A', 'Allosteric'),
+        ('U', 'Unspecified')
     )
     compound = models.ForeignKey(Compound)
     activation_mode = models.CharField(
         'Activation mode', max_length=1, choices=ACTIVATION_MODES)
     ppi = models.ForeignKey(Ppi)
-    pdb_id = models.CharField('PDB ID', max_length=4)
+    pdb_id = models.CharField('PDB ID', max_length=4, blank=True, null=True)
     nb_copy_compounds = models.IntegerField(
         'Number of copies for the compound')