THE LINKING OF SPIRAZINES 



Since a single polypeptide spiral, being of 

 about the same diameter as the benzine ring, 

 measures only about five Angstrom units (5 x 10'^ 

 cm. ) in diameter, it is evident that even the small- 

 est bacteria, and all other fibrous forms of living 

 matter which are visible under the microscope, 

 must consist of aggregates of large numbers of 

 such spirals. The fact that about three-fourths 

 of the weight of living tissues is water seems to 

 indicate that the polypeptide spirals of such tis- 

 sues are not arranged in closely packed formation 

 like the molecules of a crystal, but rather in some 

 sort of open or spaced-apart formation. 



Chemical union between adjacent spirals may 

 take place through either the amino, the carbonyl, 

 or the alpha carbon groups. Three different 

 things, taken two at a time, can produce six dif- 

 ferent combinations. Some of these can be elimi- 

 nated immediately as representing reactions 

 w^hich do not take place chemically. For example, 

 two amino groups will not unite directly with each 

 other, nor will two carbonyl groups be very likely 

 to unite with each other permanently. The amino 

 hydrogen from one spiral may, however, unite 

 with the carbonyl oxygen of an adjacent spiral so 



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