107 

 functional domain of each protein rapidly lost activity over 

 time even at 3 0°C and was protected from inactivation by 

 cof actor much better than by substrate. From the data 

 obtained, it appears that SP-II was stabilized to a slightly 

 greater degree than the SP-I (about 6% greater when NADP"^ 

 was present at incubation and about 4% greater for SHK) . 

 Substrate protection of the DQT functional domain of the two 

 proteins with DHQ was not performed at this time. 



