diff --git a/src/dscience/biology/parser/Pdbml.d b/src/dscience/biology/parser/Pdbml.d
index 2389f92..02211ee 100644
--- a/src/dscience/biology/parser/Pdbml.d
+++ b/src/dscience/biology/parser/Pdbml.d
@@ -18,6 +18,7 @@ private import tango.io.Stdout;

 alias Document!(char) XML;

+
 public class Pdbml{
     private File                    pdbml;
     private XmlPath!(char).NodeSet  root;
@@ -66,7 +67,7 @@ public class Pdbml{
         return molecules;
     }

-    public IProtein getProtein(uint model, size_t entity_id, char[][][]peptides ...){
+    public IProtein getProtein(uint model, size_t entity_id, char[][][]peptides){
         auto struct_ref_seqCategory  = root.descendant("struct_ref_seqCategory");
         auto struct_ref_seq          = struct_ref_seqCategory.child("struct_ref_seq").dup;
         IMolecule[][]   molecules       = new IMolecule[][](peptides.length);
@@ -85,7 +86,7 @@ public class Pdbml{
             }
         }
         molecules.length = index;
-        createDisulfideBond(molecules, strands);
+        /*createDisulfideBond*/ helper(molecules, strands);
         IProtein protein = new Protein(proteinName, molecules);
         protein.doPeptideBond();
         return protein;
@@ -179,13 +180,31 @@ public class Pdbml{
             }
         }
     }
-
-    private void createDisulfideBond(IMolecule[][] molecules, uint[char[]] strands){
+
+    void helper(IMolecule[][] molecules, uint[char[]] strands)
+    {
+        bool myFilter(XML.Node n)
+        {
+            /*
+            //segfaults
+            bool a1 = (n.query.child("conn_type_id").nodes[0].value == "disulf");
+            bool a2 = (n.query.child("ptnr1_label_asym_id").nodes[0].value in strands) !is null;
+            bool a3 = (n.query.child("ptnr2_label_asym_id").nodes[0].value in strands) !is null;
+            return a1 && a2 && a3;
+            */
+            //works
+            return n.query.child("conn_type_id").nodes[0].value == "disulf" &&
+                (n.query.child("ptnr1_label_asym_id").nodes[0].value in strands && n.query.child("ptnr2_label_asym_id").nodes[0].value in strands);
+        }
         auto struct_connCategory    = root.descendant("struct_connCategory");
-        auto struct_conn            = struct_connCategory.child("struct_conn").filter((XML.Node n)  {
-                                                                                                        return n.query.child("conn_type_id").nodes[0].value == "disulf" && (n.query.child("ptnr1_label_asym_id").nodes[0].value in strands && n.query.child("ptnr2_label_asym_id").nodes[0].value in strands);
-                                                                                                    }).dup;
-        foreach(molecule; struct_conn){
+        auto struct_conn            = struct_connCategory.child("struct_conn").filter(&myFilter).dup;
+        createDisulfideBond(molecules, strands, struct_conn);
+    }
+
+    void createDisulfideBond(IMolecule[][] molecules, uint[char[]] strands, XmlPath!(char).NodeSet struct_conn)
+    {
+        foreach(molecule; struct_conn)
+        {
             size_t molecule1Index       = Convert.to!(size_t)(molecule.query.child("ptnr1_label_seq_id").nodes[0].value) - 1;
             size_t molecule2Index       = Convert.to!(size_t)(molecule.query.child("ptnr2_label_seq_id").nodes[0].value) - 1;
             char[] ptnr1_label_asym_id  = molecule.query.child("ptnr1_label_asym_id").nodes[0].value;