From 574177fab79a3e756403f1a843d179a4278a68f0 Mon Sep 17 00:00:00 2001
From: James Krieger <jamesmkrieger@gmail.com>
Date: Mon, 6 Nov 2023 17:10:25 +0100
Subject: [PATCH] better fix

---
 prody/proteins/pdbfile.py | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/prody/proteins/pdbfile.py b/prody/proteins/pdbfile.py
index 5fbd270f9..9fcbe8edf 100644
--- a/prody/proteins/pdbfile.py
+++ b/prody/proteins/pdbfile.py
@@ -1242,12 +1242,7 @@ def writePDBStream(stream, atoms, csets=None, **kwargs):
         Default is **False**, which means using hexadecimal instead.
         NB: ChimeraX seems to prefer hybrid36 and may have problems with hexadecimal.
     :type hybrid36: bool
-    """
-    keepACSI = False
-    if hasattr(atoms, 'getACSIndex'):
-        initialACSI = atoms.getACSIndex()
-        keepACSI = True
-        
+    """    
     renumber = kwargs.get('renumber', True)
 
     remark = str(atoms)
@@ -1266,8 +1261,10 @@ def writePDBStream(stream, atoms, csets=None, **kwargs):
     if coordsets is None:
         raise ValueError('atoms does not have any coordinate sets')
 
+    had_atoms = False
     try:
         acsi = atoms.getACSIndex()
+        had_atoms = True
     except AttributeError:
         try:
             atoms = atoms.getAtoms()
@@ -1442,7 +1439,8 @@ def writePDBStream(stream, atoms, csets=None, **kwargs):
     num_ter_lines = 0
     for m, coords in enumerate(coordsets):
 
-        atoms.setACSIndex(m)
+        if had_atoms:
+            atoms.setACSIndex(m)
         anisous = atoms._getAnisous()
         if anisous is not None:
             anisous = np.array(anisous * 10000, dtype=int)
@@ -1618,8 +1616,8 @@ def writePDBStream(stream, atoms, csets=None, **kwargs):
             
     write('END   ' + " "*74 + '\n')
 
-    if keepACSI:
-        atoms.setACSIndex(initialACSI)
+    if had_atoms:
+        atoms.setACSIndex(acsi)
 
 writePDBStream.__doc__ += _writePDBdoc