editing .md2 file in blender

I am new to blender…I just want to edit some .md2 models in blender…but how can I change the center of the md2 object…I imported the .md2 file in blender and when trying to change the center of the object the error was displayed “cannot change a center of a mesh with vertex keys”…if anyone can help on this…Are .md2 models editable in blender or not?