Chain identifier should be blank not A: ATOM   4095 ZN    ZN A 517      -4.176  11.231 111.019  1.00 18.92      A   ZN  
Chain identifier should be blank not B: ATOM   4123 ZN    ZN B 518      18.303  48.323 135.607  1.00 27.86      B   ZN  

1