BIOGRAPHICAL MEMORANDA 



which might furnish an intelligible interpretation of the Harden and 

 Young equation. Following the same line of reasoning that had been 

 so successful in making metabolic processes more easily comprehensible 

 as a result of the dislocation of substrate molecules under the influence 

 of catalysts with appropriate affinities for hydrogen, it soon occurred 

 to him that the ring configuration of a sugar, representing by far the 

 most stable one, might prevent an effective attack by a biological cat- 

 alyst, and that a primary modification of the structural pattern might 

 be a prerequisite for initiating a subsequent break of the molecule be- 

 tween the third and fourth carbon atoms. In coupling this notion 

 with the equally plausible one that Harden and Young's ester, as a 

 hexose diphosphate, would probably be formed as a result of two con- 

 secutive processes, involving hexose monophosphate as a first product, 

 the concept emerged that the formation of this monophosphate per se 

 might be the means by which the structural modification was accom- 

 plished. Due to the strongly polar nature of the phosphate group the 

 first phosphorylation would cause a redistribution of various bond 

 strengths, and by assuming that this esterification involved the hy- 

 droxyl group at carbon atom five after opening of the ring, a case 

 could be made out for the specific weakening of the central carbon- 

 carbon bond, as indicated in the following diagram : 



H 



! li 

 C 6 ^c 5 ^C 4 c 3 ^c 2 C 1 , 



! i I! 



O— :P0 4 = OH 



where the dotted lines represent weakened, the dash-dotted ones rein- 

 forced bonds. As a consequence of the specific activation of hydrogen 

 attached to carbon atom four, this hydrogen could then be transferred 

 to carbon atom three, at the same time causing a rupture of the car- 

 bon chain. 



This ingenious hypothesis implied, therefore, a reaction sequence 

 of the kind, 



( i ) G 6 H 12 6 + H 3 P0 4 -> C 6 H n 5 P0 4 H 2 + H 2 0, and 



(2) CeHnC^PC^Ha -> C 3 H 5 2 P0 4 H 2 + G 3 H 6 3 , 



in which a triose molecule is generated alongside a triose-phosphate 

 molecule as a direct consequence of the primary esterification. Under 



92 



