R. L. AJRTH 



267 



of an inhibitor. During the course of this type of experiment, 

 secondary additions of bovine plasma albimiin also were tested. 

 Results of one of these experiments are presented in Fig. 4. 



An enzyme preparation that had some activity was assayed with 

 albumin which was added either before the reaction was initiated 

 with DPNH or after 4 minutes. Upon secondary addition of plasma 

 albumin (curve A), there was an immediate increase in light in- 

 tensity to a value approximating that of curve B — in which case the 

 albumin was added before the reaction was started. The gradual in- 

 crease in light intensity with time in the absence of albumin (Fig. I) 

 may be explained on the basis of (a) increase in the amount of 

 substrate — luciferin, (b) increase in the amount of active enzyme, 

 (c) production of some component (s) — other than luciferin — essen- 



60 



50 



^ 40 

 W 



z 



Ul 



I- 

 z 30 



H 

 I 

 O 

 3 20 



10 



o 



I 



2 3 4 5 6 



TIME = MINUTES 

 Fig. 4. Effect of secondary crystalline bo\iiie plasma addition on fungal bio- 

 luminescence in vitro. Reaction conditions: B: bovine plasma albumin, 12 mg; 

 luciferase (0-75% (NH4),,SO, fraction), 3.5 mg; luciferin, 0.10 ml; DPNH, 0.46 

 umoles; buffer, same as in Fig. 2, to bring to a final volume of ,3.0 ml. A: Same 

 as B, except that the albumin was added 4 minutes after tiie reaction was initiated 

 with DPNH. 



