THE STRUCTURE OF INSULIN 



F. SANGER, Department of Biochemistry, University of Cambridge, 



Cambridge, England 



In recent years protein chemistry has been so extensively 

 reviewed from many different points of view that it would seem 

 purposeless to prepare another general article on the subject; 

 rather it is proposed to give an account of our own work of the 

 last decade which has led to the elucidation of the structure of 

 the protein insulin. It is hoped in this way to illustrate the 

 newer methods which are available for the study of proteins and 

 to indicate some of the present trends in protein chemistry. 



The foundations of the present study were laid by much 

 painstaking work carried out at a time when insulin was avail- 

 able only in very small quantities and was of doubtful purity. 

 To these early investigations we owe the initial hypotheses of 

 this work, which are that insulin as purchased is virtually a pure 

 substance and that it is a protein containing 16 different amino 

 acids (for references, see ref. 17). We may further assume, fol- 

 lowing the pioneers of protein chemistry, that the amino acids 

 are joined together through peptide bonds. 



Molecular Weight 

 When studied under normal conditons in aqueous solution 



434 



