Chain identifier should be blank not B: ATOM   4545 MG    MG B 570      19.992   0.971   5.805  1.00 43.46      B   MG  
Chain identifier should be blank not A: ATOM   4508 MG    MG A 571       0.579   6.824  26.882  1.00 36.13      A   MG  

1