Chain identifier should be blank not A: ATOM   2719 MG    MG A 337      18.520 376.660 723.630 31.00 73.10      A   MG  
Chain identifier should be blank not A: ATOM   2720 MG    MG A 338      15.160 174.880 126.620 51.00 70.60      A   MG  
Chain identifier should be blank not A: ATOM   2721 MG    MG A 339      19.130 979.480 126.120 51.00 50.20      A   MG  

1