21. 



Direct Ch -smical U nio n "b 3 1 ;v o jn Sp i r "^J . r- . 



Ws hav3 har-atnl'crs aGSurnad that c^nnDction 

 "between adjacent spirals t.ak^s plac3 only through 

 the hydrocarbon side chains attached to the alpha 

 carbon atcms. This is undoubtedly the priir.ary 

 mode of connection, but af t :r tv/o spirals are 

 thus connected together there may bj a secondary 

 connection between th 3 arnino groups of on^ spiral 

 and th3 carbonyl groups of the other. If both 

 spirals have the sa:!ne dirsction of twist, the 

 amino hydrogsn cf on 3 spiral will b3 posit ion jd 

 directly opposite the carbnnyl cxyg i^n of th3 other 

 spiral, so that there will bo a tsndsncy for wat 3r 

 to split ^ff, leaving the amino nitrogen to combine 

 directly with the carbonyl carbon. In this manner 

 there m.ay be produced either thj pyrrole or the 

 pyrimidine ring, depending on wheth3r the primary 

 connection was of the beta or of the gamma type. 

 As shcv\rn in the follov/ing diagrams, various dif- 

 ferent configurations can b3 produced by joining 

 adjacent spirals directly to 3ach other: 



V-r^' 



