49 

 enzyme activities of PAT, ADH, ADT and SDH (DQT activity was 

 coincident with SDH activity; not shown) . Although ADT and 

 ADH activities were not found in crude extracts of C. 

 sorokiniana, they were located in DEAE-cellulose fractions 

 at very low activities as shown in Fig. 3-2A. ADH was 

 specific for cof actor NADP*. Prephenate dehydratase and 

 prephenate dehydrogenase activities were not found in these 

 column fractions. The ADH and ADT activities overlapped 

 those of PAT, DQT, and SDH in the KCl gradient fractions. 

 The coeluting DQT and SDH activity peak fractions, as shown 

 in Fig. 3-2B, were pooled, dialyzed and applied to an HA 

 column where they once again coeluted, this time in the wash 

 fraction, data not shown. 

 PAT in C. sorokiniana 



Several of the unique properties earlier shown for 

 prephenate aminotransferase in N. silvestris suspension 

 cells (5) were studied in C. sorokiniana extracts. A high 

 temperature optimum of about 70°C for PAT was also found in 

 the alga extract as shown in Fig. 3-3. In Table 3-2, it is 

 shown that PAT from Chlorella has a preference for GLU as 

 the amino acid donor in combination with the keto acid 

 substrate, PPA. As found in higher plants, ASP was utilized 

 at about 50% of the activity with GLU. Slight activity was 

 seen with TYR as the amino acid donor in C. sorokiniana but 

 not in N. silvestris . 



