18 

 (12) and after wounding of potato (59) . 



Aroqenate dehydratase . ADT activity was first 

 determined in N. silvestris cells by Jung et al . (43) . The 

 enzyme was localized in spinach chloroplasts and allosteric 

 regulation (activation by TYR and inhibition by PHE) was 

 studied (43) . Siehl and Conn (75) partially purified ADT 

 from Sorghum bicolor and studied some kinetic and regulatory 

 properties. 



Rationale for focus upon the post-prephenate enzymes. 

 The rationale in choosing to study some aspects of the post- 

 prephenate enzymes for this dissertation is my long-term 

 objective to follow up earlier work with molecular-genetic 

 approaches. Studies of the individual enzymes may shed some 

 light as to the multiplicity of compartment at ion. The 

 merits are as follows. A) Prephenate aminotransferase (i) 

 has been characterized and a well -developed HPLC assay 

 exists (5) , (ii) has important biotechnological application 

 due to its unique aminotransferase properties and the value 

 of its product, L-arogenate, and (iii) can be purified by an 

 established procedure (7) . B) Arogenate dehydrogenase (i) 

 has an established purification methodology (8) for 

 providing purified protein for antibody production that may 

 be used to probe cDNA libraries, and (ii) is easily assayed 

 f luorometrically. C) Arogenate dehydratase has an 

 established HPLC assay (43) , but is by far the most 

 difficult of the three enzymes to assay and purify. 



