390 Chemical Constitution of Starch [June-September 



assumption of one dl-carbonyl linklng; or, there are nine mono- 

 carbonyl bonds, which necessitates the assumption of a ring 

 structure. 



Let US consider the first possibility, for which a di-carbonyl 

 group is assumed. It is evident that none of the y bonds is a car- 

 bonyl (there is no di-carbonyl bond in maitose). It is also easy to 

 see that none of the ß bonds in the dextrin residue is di-carbonyl. 

 Free protodextrin I reduces Fehling Solution, which indicates that 

 it contains a free carbonyl radical. At the two linkings between 

 the three glucose molecules of this dextrin, only two carbonyl radi- 

 cals are f ormed upon hydrolysis : these are mono-carbonyl. 



If a di-carbonyl linking were present in the amylogen, it could 

 be only one of the a. bonds. By use of the sign ( < ) to denote a 

 carbonyl bond, and putting di-carbonyl bonds in the place of a link- 

 ings, the formula of amylogen may be written as follows : 



(Co) > (C,2) 



A 

 (Ce) > (QO 



A 

 (Ce)><(Ci2) 



Under this scheme, hydrolysis would give no maitose; but, on 

 the other band, two different kinds of dextrin, one possessing no 

 reducing power. This is not the case and, therefore, there is no 

 di-carbonyl bond in the amylogen nucleus. 



This conclusion naturally suggests the other possibility. The 

 nature of the hydrolytic products of amylogen that have been 

 istudied would make it difficult to imagine an a or a y linking in a 

 ring structure. Such a structure, Synkiewski claims, may be easily 

 made up of ß bonds, and there are two possibilities : 



[-(Ce)— a— (Ce)— 7— (Ce) 

 I 



ß 

 I 

 (A) ß (Ce)— a— (Ce)- 7— (Ce) 



ß 

 -(Ce)-a-(Ce)-T-(Ce) 



