Chain identifier should be blank not A: ATOM   2939 MG    MG A 365      48.416  -1.936  22.894  1.00 35.43      A   MG  
Chain identifier should be blank not B: ATOM   2983 MG    MG B 366      58.865  50.360  53.494  1.00 51.05      B   MG  

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