448 



A. G. PASYNSKIÏ 



accelerated the reaction and the titre of ascorbic acid fell to point C, but later 

 there was a corresponding diminution in diflfusional loss through the membrane 

 owing to which a new stationary state, DE, was established for the system with 

 the enzyme, just as constant over a period as the original state AB, but at a lower 

 level. It is interesting that the state DE was established at a level far nearer to 

 AB than that of the minimum C. Thus, the transition from one stationary state 

 to another does not follow a smooth curve ABDE, but passes through a minimum 

 BCD. Similar results have been obtained using concentrations of ascorbic acid 

 (in the mixture) of 0-3 and i-i% with corresponding changes in the concentra- 

 tions of the inflowing hquids (07 and 2-5" o) and in the level of the stationary 

 concentration (Fig. 4). 



A 



E 

 -• — • — • 



40 60 80 100 120 140 160 180 



Time, min 



Fig. 4. Enzymic oxidation of ascorbic acid under flowing conditions at different 



concentrations. 



If the enzymes were added in two portions each of 0-5 mg in i ml of water 

 with an interval of 120 min between the additions (Fig. 5), then, after the 

 establishment of the original stationary state AB (without the enzyme) and the 

 introduction of the first portion of enzyme, a transition through a minimimi, 

 BCD, was observed, followed by the establishment of a stationary state, DE, 

 which was maintained for 90 min. When the second portion of the enzyme was 

 introduced at point E, the curve was once more seen to pass through a minimum 



>< s 

 — • — •_• 



/■ 



,-•—•—•—•-,— •—• G 



F 



60 80 100 120 140 160 180 200 220 240 260 260 300 



Time, min 



Fig. 5. Enzymic oxidation of ascorbic acid under flowing conditions when the 

 enzyme is added in two portions. 



