TRISACCHARIDES 



125 



up into one molecule of glucose and one of fructose,* as is 

 explained by the formulae given below for these sugars : — 



XH- 



-O- 



O 



CHOH 



I 

 CHOH 



I 

 CHOH 



I 

 — CH 



I 

 CH2OH 



Glucose 



CH- 



Melecitose. 



CH2OH 



I 



c 



I 



CHOH 



I 

 CHOH 



I 

 CH 



I 

 -CH^ 



Fructose 



Turanose. 

 O- 



-CH- 







-O— I CHOH 



I 

 CHOH 



I 

 CHOH 



O 



CH 



CH2OH 



Glucose 



CHOH 



I 

 O CHOH 



CHOH 



-i„ 



CH2OH 

 Glucose 



CHjOH 

 COH 



CHOH 



I 

 CHOH 



o 



— CH, 

 Fructose 



STACHYOSE. C^.H^.O,,, 4H2O. 



This substance occurs in the tubers of Stachys tuberifera 

 and in a large number of leguminous seeds. f It forms plate- 

 like crystals, which dissolve readily in water to give a faintly 

 sweet solution, which is dextro-rotatory (ajj = + 148°). It 

 does not reduce Fehling's solution. When boiled with dilute 

 mineral acid it yields one molecule each of glucose and levulose, 

 and two molecules of galactose.^ 



GENTIANOSE. C^^^^.Oi^. 



This trisaccharide occurs in the roots of Gentiana lutea. 

 On hydrolysis by mineral acids it is converted into two 

 molecules of glucose and one of fructose. Hydrolysis by 



* Kuhn and von Grundherr : " Ber. deut. chem. Gesells.," 1926, 59, 

 1655. Zemplen : id., 2230, 2539. Leitch : " J. Chem. Soc," 1927, 588. 

 t Tanret : " Connpt. rend.," 1912, 155, 1526. 

 X Planta and Schulze : " Ber. deut. chem. GescUs.," 1891, 24, 2705. 



