26 Spirazines 



cine, and isolencine are evidently the fragments 

 of the complexes which connected adjacent spirals 

 in the original mass, because if the particular 

 spirals which carried these branched side chains 

 had been connected by means of their amino and 

 carbonyl groups, then it is unlikely that they 

 would have produced the alpha amino acid groups 

 again upon hydrolysis. In valine and isoleucine 

 the triple junction occurs at the beta carbon atom, 

 whereas in leucine it occurs at the gaimna carbon 

 atom. Phenylalanine and tyrosine also exhibit a 

 similar branching at the gamma carbon atom. 

 No amino acid has ever been obtained from nat- 

 ural proteins in which such a junction occurs at 

 any point beyond the gamma carbon atom, nor 

 would we expect to find such structures because at 

 more remote points the side chains would have too 

 much freedom of movement to produce the triple 

 junction spontaneously. Aspartic acid appears 

 to have come from two spirals which were con- 

 nected directly by means of their alpha carbon 

 atoms without the presence of any intermediate 

 atoms. Glutamic acid differs from aspartic acid 

 in that it has one more CH2 group, which evi- 

 dently formed the connecting link between two 

 adjacent spirals, although it may also have 

 formed a triple junction between three adjacent 

 spirals. 



