Script

#formatador de pdb
def add_chain_ids(input_pdb, output_pdb, chain_ids=('A', 'B')):
    with open(input_pdb, 'r') as infile:
        lines = infile.readlines()

    current_chain = 0
    atom_count = 0

    with open(output_pdb, 'w') as outfile:
        for line in lines:
            if line.startswith("ATOM"):
                if "TP3M" not in line:
                    atom_count += 1

                    if atom_count > 9951:   #Mude conforme o arquivo
                        current_chain = (current_chain + 1) % len(chain_ids)
                        atom_count = 1

                    modified_line = line[:21] + chain_ids[current_chain] + line[22:]
                    outfile.write(modified_line)
                else:
                    outfile.write(line)
            else:
                outfile.write(line)

    print("Arquivo formatado!! :D")


input_pdb = 'structure.pdb'
output_pdb = 'structure_chains.pdb'
add_chain_ids(input_pdb, output_pdb, chain_ids=('A', 'B'))