STARCH 157 



glucosido-maltose which contains both an a- and a jS-Hnking. 

 These facts are best explained by the following formulae : — 



1/3 a\ in a\ 10 



aj3-Hexa-amylose Maltodextrin-a j3-Glucosido-maltose 



From which it appears that ajS-hexa-amylose is composed of 

 six hexose residues united together by four ^- and two a- 

 linkages ; the conversion of this into maltodextrin-a results 

 from the fission of one jS-linkage ; the further fission of yet 

 another )3-linkage yields 2 molecules of the trisaccharide 

 jS-glucosido-maltose * which must have the constitution — 



o ^ 



I I 



CH, . CH . CH(CHOH),-C . HOH iso-maltose. 



P O J 



CH— (CHOH),— CH . CHOH— CHg > 



Oo 



CHjOH CHOH . CH(CHOH) 



' o— 



,— CH 



maltose. 



j3-glucosido-maltose 



since it is broken up by emulsion into glucose and maltose 

 and by maltase into glucose and iso-maltose, showing it to 

 have both an a- and jS-linking. 



On the other hand, the amylose constituent of the starch 

 grain would in Ling and Nanji's opinion appear to be an 

 a-hexa-amylose f of the formula — • 



/ \ 



|a a 



e\ b 



K / 



in which the six sides, a, h, c, d, e, and /, represent glucose 

 anhydrides, CgHioOg, united together through oxygen atoms at 



* j3-Glucosido-maltose yields an osazone, m.p. 122°. Ling and Nanji : 

 loc. cit., p. 2679. 



t Ling and Nanji : " J. Chem. Soc." 1923, 123, 2684. 



