544 Hexosephosphate formed by Yeast-juice from Hexose, etc. 



CHO 



H-C-OH 



OHO-H 



H-C-OH 



HCOH 



CH 2 OH 

 Glucose. 



CHO 



OHCH 



OHCH 



HCOH 



HCOH 



CH 2 OH 

 Mannose. 



and all these sugars have the same enolic form 



CHO 



CHOH 



CHOH^ 



CHOH^ 



CHOH 



CH 2 OH 



Glucose and mannose. 



CHOH 

 II 



COH 

 CHOH ~ 

 CHOH ^ 

 CHOH 

 CH 2 OH 



Enolic form. 



CH 2 OH 

 I 



CO 

 OHCH 

 H-COH 

 HCOH 



(JH 2 OH 



Fructose 



CH 2 OH 

 I 



CO 



CHOH 

 CHOH 

 CHOH 

 CH 2 OH 



Fructose. 



and are converted into one another in alkaline solution,* and it is conceivable 

 that the hexosephosphate is a derivative of this enolic form. 

 If the reaction take place according to the equation : 



2C 6 H 12 6 + 2R' 2 HP0 4 = 2CQ 2 + 2C 2 H 6 O + C 6 H 10 O4(PO4E' 2 ) 2 +2H 2 O, 



two molecules of sugar are concerned, and another possibility is that the 

 phosphoric acid groups are attached to a new molecule, which is formed by 

 the combination of portions of each of these two sugar molecules. In this 

 case, also, the hexosephosphoric acid might be expected to have the same 

 composition when formed from different sugars. 



Summary. — 1. The compound formed during the accelerated fermenta- 

 tion of glucose, fructose, and mannose by yeast-juice, in the presence of 

 a soluble phosphate, is a salt of an acid which probably has the formula 

 C 6 Hio04(P0 4 H 2 ) 2 , and may be isolated by precipitation of its lead salt. 



2. The free acid may be obtained in solution by decomposing this lead 

 salt with sulphuretted hydrogen. 



3. The acid is very unstable and readily decomposes on keeping, or on 

 evaporating even at ordinary temperatures in a vacuum over sulphuric acid, 

 with formation of a reducing substance and phosphoric acid. 



4. It reduces Fehling's solution only after some hours in the cold, rapidly 

 on boiling, whilst no osazones or hydrazones have been obtained from it. 



* Lobry de Bruyn, ' Eec. Trav. Chim.,' 1895, vol. 14, p. 201. 



