Merge pull request #311 from cxhernandez/master

Forgotten zinc

wrappers/python/simtk/openmm/app/amberprmtopfile.py

@@ -119,6 +119,8 @@ class AmberPrmtopFile(object):
                     element = elem.sodium
                 elif upper.startswith('MG'):
                     element = elem.magnesium
+                elif upper.startswith('ZN'):
+                    element = elem.zinc
                 else:
                     try:
                         element = elem.get_by_symbol(atomName[0])

wrappers/python/simtk/openmm/app/pdbfile.py

@@ -116,6 +116,8 @@ class PDBFile(object):
                             element = elem.lithium
                         elif upper.startswith('K'):
                             element = elem.potassium
+                        elif upper.startswith('ZN'):
+                            element = elem.zinc
                         elif( len( residue ) == 1 and upper.startswith('CA') ):
                             element = elem.calcium
                         else: