104 

 no effect on activity when tested at pH 7.0, 8.6, or 9.5. 



Table 5-2. Effect of PCMB on Enzyme Activities 







mM 





Percent , 



. 5 mW DTT 



Percent 



Protein 



Enzyme 



PCMB 



Inhibition 



Prevention 



Reversal 



Activation 



SP-1 



SDH 



0.000 



0.0 



NA 



NA 



NA 





SDH 



0.125 



100 



100 



0.0 



NA 





SDH 



0.250 



100 



100 



0.0 



NA 





SDH 



0.500 



100 



95 



0.0 



NA 





SDH 



1.000 



100 



81 



0.0 



NA 





DQT 



0.050 



0.0 



NA 



0.0 



50 





DQT 



0.100 



0.0 



NA 



NA 



50 



SP-II 



SDH 



0.000 



0.0 



NA 



NA 



NA 





SDH 



0.500 



100 



96 



0.0 



NA 





DQT 



0.050 



0.0 



NA 



NA 



55 



DISCUSSION 



A shallow ammonium sulfate gradient on a Celite 545 

 column revealed about 6 peaks of SDH activities. All SDH 

 activity peaks had DQT activity as well. No differential 

 properties were found between the five overlapping peaks 

 containing SDH and DQT activities which eluted in the 

 gradient from 55% to 45% of (NH4)2S04 saturation. These 

 could be isoforms of SP-I or artifacts of the column 

 chromatography. The sixth peak (also referred to as SP-II) 

 had several differential properties when compared to SP-I 

 which contained all of or some of the five activity peaks 

 from the Celite 545 shallow gradient column profile. A 

 difference of molecular mass of about 3,000 was determined 



