Calculating Protein Mass - https://rosalind.info/problems/prtm/

 mmt = {  
 "A":71.03711,  
 "C":103.00919,  
 "D":115.02694,  
 "E":129.04259,  
 "F":147.06841,  
 "G":57.02146,  
 "H":137.05891,  
 "I":113.08406,  
 "K":128.09496,  
 "L":113.08406,  
 "M":131.04049,  
 "N":114.04293,  
 "P":97.05276,  
 "Q":128.05858,  
 "R":156.10111,  
 "S":87.03203,  
 "T":101.04768,  
 "V":99.06841,  
 "W":186.07931,  
 "Y":163.06333 }  
 input_file = open("rosalind_prtm.txt", "r")  
 AA = input_file.read().replace('\n','')  
 print(sum([mmt[x] for x in AA]))