INTEKACTIOX OF PLASMA PHOSPHATE WITH THE PHOSPHOPaS COMPOTXDS 475 



ester was in exchange equilibrium with the inorganic P present in the 

 corpuscles. The re-synthesis of" the acid soluble organic P comj)()un(ls 

 must thus l)e a fast process and, from the fact that with increasing time 

 the ratio between the specific activity of the ester P and inorganic P 

 of the corpuscles only slightly increases and yet strongly differs from 1 , 



Table 1. — Activation in Vitro of Acid-.Solvhle Phospho- 

 rus Present in the Corpuscles 



Relative specific activities of corpuscles' phosphate and of organic 

 acid-soluble phosphorus present in the corpuscles, taking the spe- 

 cific activity of the plasma-phosphate at the end of the experi- 

 ment to be = 1. 



Time 



Ivcl. Spec, activity 

 of Corp. org. acid- 

 soluble V 



S. 



m 



Hab])it G 



Rabbit H 



, I on min. 



( 90 min. 



30 min. 



90 min. 



17.") mill. 



0.14 

 0.21 

 0.11 

 0.23 

 0.36 



we must conclude that only a part of the diverse organic phosphorus 

 compounds present in the corpuscles is renewed and thus activated in 

 the course of the experiment while the other part, composed of 

 diphosphoglycerate, hexosephosphate and other compounds remains, at 

 least practically, inactive. This conclusion is supported by the results 

 of the following experiments. Instead of destroying the total esters w^e 

 hydrolysed<i) them with 1 n. HCl or H2SO4 for 100 min at lOO^ and deter- 

 mined the specific activity of the hydrolysed P. While the average ester 

 P secured from the corpuscles of a rabbit (G, comp Fig. 1) was found to 

 have a specific activit}^ amounting to 55% of the corpuscle inorganic P 

 the corresponding figure for the hydrolysable ester was 80%. In the 

 case of another rabbit (H), the figures were 53% and 100% respecti- 

 vely 2). From the facts mentioned above, it follows that the exchange 



^^^ Under these conditions, diphospho-1-glycerate and also hexosediphosphate 

 are only hydrolysed to a negUgible resp. small extent (G. Warweg and E. Stearns, 

 ./. Biol. Chem. 115, 567 (1936). 



^-^The difference between the rate of activation of the "hydrolysable" and 

 "nonhydrolysable" fractions is still better brought out when comparing the specific 

 activity of the pyrophosphate, obtained from adenosintriphosphale after 7 min 

 hydrolysis, to that the residual P, as found in a recent investigation tli(> icsidt 

 of whicli will V)c published shortly. 



