Iterating through a Fasta file Dictionary created using Biopython

I have a problem iterating through a dictionary where the sequence should be ACTGDEDQ..., but it includes some other stuff Biopython adds when it parses a FASTA file. If I just print seq_record.seq it prints the sequence, and does not include extra stuff. However, if I print the dictionary it includes extra stuff not part of the polypeptide, and the "for loop" will not iterate through it. This one step has been annoying me forever. Does anyone know what to do?


from Bio import SeqIO

file = open("Zaza.fasta.txt")
for seq_record in SeqIO.parse(file, "fasta"):
protein_dict[seq_record.id]=seq_record.seq

def Filter_By_Molecular_Weight(prot_dict):
acidsCount = {
"A": {"count":0, "weight":89.1288},
"B": {"count":0, "weight":132.64625},
"C": {"count":0, "weight":121.1888},
"D": {"count":0, "weight":133.1386},
"E": {"count":0, "weight":147.1655},
"F": {"count":0, "weight":165.2266},
"G": {"count":0, "weight":75.1019},
"H": {"count":0, "weight":155.1911},
"I": {"count":0, "weight":131.2094},
"K": {"count":0, "weight":146.2241},
"L": {"count":0, "weight":131.2094},
"M": {"count":0, "weight":149.2486},
"N": {"count":0, "weight":132.1539},
"P": {"count":0, "weight":115.1667},
"Q": {"count":0, "weight":146.1807},
"R": {"count":0, "weight":174.2375},
"S": {"count":0, "weight":105.1282},
"T": {"count":0, "weight":119.1551},
"V": {"count":0, "weight":117.1826},
"W": {"count":0, "weight":204.2632},
"X": {"count":0, "weight":145.3726364},
"Y": {"count":0, "weight":181.226},
}

for aa_name,aa_seq in protein_dict.iteritems():
acidsCount[aa_seq]["count"]=acidsCount[aa_seq]["count"]+ 1

total=0
for acid in acidsCount:
total=total+(acidsCount[acid]["count"]* acidsCount[acid]["weight"]/1000)
return total

print Filter_By_Molecular_Weight(protein_dict)