242 ORIGIN OF STRUCTURES AND FUNCTIONS 



they would be quite indifferent in the form of free amino 

 acids. G. R. Tristram^- sums the matter up as follows: 



It is now appreciated that the properties of side chains in a 

 protein are not simple functions of the properties of the free 

 amino acids, but are, in fact, highly complex functions dependent 

 on many factors including the relative distribution of side chains 

 in the main peptide chain and in the folded native protein. 



The order in which the amino acid residues are arranged 

 in the peptide chains of native proteins or biologically impor- 

 tant peptides isolated from organisms has long attracted the 

 attention of scientists. The elucidation of this problem has, 

 however, been attended by a very large number of technical 

 difficulties.* 



The first reasonably successful attempt to establish the 

 order in which all the amino acid residues are arranged in a 

 single protein-like substance was made by K. Felix and his 

 colleagues^ ^ on the protamine of herring sperm, clupeine. 

 They considered that the molecule of clupeine is made up of 

 no more than 33 amino acid residues, namely, 22 of arginine, 

 2 of alanine, 2 of serine, 3 of proline, 3 of valine and 1 of 

 hydroxyproline. The unusually small number of amino acid 

 residues and absence of any great diversity, in particular the 

 extreme predominance of arginine, greatly simplified the task 

 of studying this peculiar protein. In Felix' opinion the amino 

 acids in the polypeptide chain of clupeine are arranged in a 

 rather regular way ; there are always a series of four arginine 

 radicals in a row along the chain followed by two residues 

 of other amino acids and then again four arginine residues, 

 etc. 



M. Bergmann^^ put forward the hypothesis that the 

 polypeptide chains of other proteins besides clupeine are 

 constructed similarly and that they also contain a definite 

 repetitive sequence of amino acid residues. For example, if 

 there are 54 lysine residues in edestin out of a total of 432, 

 this means that every eighth amino acid residue in the poly- 

 peptide chain of edestin will be lysine. Similarly, in ox 

 globin, each of the 36 lysine residues will be separated from 



* The earlier efforts in this direction have been reviewed by R. L. M. 



Synge, Chein. Rev., 52, 135 (1943). — Translator. 



