Simple function to mutate a string of amino acids given their indicies

mutate_amino.py

def mutate_amino(protein_str, mutations, offset=1):
    ''' mutations: {int>mutation_idx:str>AminoID}'''
    mut_protein_str = list(protein_str)
    
    for mut_idx in mutations.keys():
        mut_protein_str[mut_idx-offset] = mutations[mut_idx] # Arg 71 His | R > H 

    mut_protein_str = ''.join(mut_protein_str)
    
    return mut_protein_str

protein_str = "MISPFLVLAIGTCLTNSLVPEKEKDPKYWRDQAQETLKYALELQKLNTNVAKNVIMFLGDGMGVSTVTAARILKGQLHHNPGEETRLEMDKFPFVALSKTYNTNAQVPDSAGTATAYLCGVKANEGTVGVSAATERSRCNTTQGNEVTSILRWAKDAGKSVGIVTTTRVNHATPSAAYAHSADRDWYSDNEMPPEALSQGCKDIAYQLMHNIRDIDVIMGGGRKYMYPKNKTDVEYESDEKARGTRLDGLDLVDTWKSFKPRYKHSHFIWNRTELLTLDPHNVDYLLGLFEPGDMQYELNRNNVTDPSLSEMVVVAIQILRKNPKGFFLLVEGGRIDHGHHEGKAKQALHEAVEMDRAIGQAGSLTSSEDTLTVVTADHSHVFTFGGYTPRGNSIFGLAPMLSDTDKKPFTAILYGNGPGYKVVGGERENVSMVDYAHNNYQAQSAVPLRHETHGGEDVAVFSKGPMAHLLHGVHEQNYVPHVMAYAACIGANLGHCAPASSAGSLAAGPLLLALALYPLSVLF"
mutations = {71:'H', 263:'H', 522:'A'}
mut_str = mutate_amino(protein_str, mutations)