Chemical System for Oxidation of lAA by Peroxidase 



207 



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Fig. 1. Changes in the ultraviolet spectrum during the oxidation of lAA (IQ-'M) 

 b>° peroxidase (IQ-'A/). Solid line, in acetate buffer (pH 5); 1, 35 sec; 2, 10 min.; 

 3, 30 min.; 4, 4 hrs.; 5, 24 hrs.; broken line in phosphate buffer, pH 7.5, after 24 

 hrs. Continuation of curve 5 over range 0.8 to 1.8 absorbancy is given in reduced 

 stale at lower left. 



to 260 m/i, region during the first 10 min., after which the rate of 

 increase of absorbancy gradually fell off. The peaks at 248 and 254 

 mix could first be distinguished after about an hour, and reached their 

 maximum in about 20 hrs. After that the peaks decreased slightly 

 (0.06 unit) during the next 3 days. In the indole region (280 mfx) ab- 

 sorption fell from 0.61 to 0.41 in the first 40 min., remained constant 

 for the next 3 hrs., and then slowly fell as a new maximum formed at 

 285 m^ during the ensuing 3 days. 



The changes observed resemble closely those recorded by Ray 

 (8) for the action on lAA of the lAA oxidase from Omphalia, and 



