dehydrogenase activity stain. Temperature and pH optima for 

 catalysis were similar for each protein, as were the 

 temperatures of inactivation. However, Km values for 

 shikimate were 0.80 and 0.36 mAT for SP-I and SP-II, 

 respectively. Antibody raised against SP-I cross-reacted 

 with SP-II, but not with Escherichia coli proteins 

 possessing the corresponding activities. Antibody screening 

 of a cDNA library of Nicotiana tabacum was used to isolate 

 clones expressing the S -protein. Functional complementation 

 of aroD and aroE E. coli auxotrophs transformed with 

 plasmids carrying cloned cDNA were successful. Activities 

 for each enzyme were 15 -fold greater in the transformed 

 mutant strains than in the wild type strain of E. coli. 

 Analysis of the amino acid sequence deduced from the cloned 

 cDNA sequence revealed homology with the appropriate 

 functional domains of the pentafunctional Arol protein of 

 Saccharomyces cerevisiae and with the monofunctional AroD 

 and AroE proteins of E. coli. The post-prephenate pathway 

 enzymes were also studied in Nicotiana silvestris suspension 

 cells. Levels of arogenate dehydratase activity changed 

 throughout a growth cycle in suspension cells. Using 

 specific antibodies, several putative cDNA clones encoding 

 prephenate aminotransferase or arogenate dehydrogenase were 

 isolated for further study. The base of comparative 

 enzymology in higher plants for the aforementioned enzymes 

 was extended to the unicellular alga, Chlorella sorokiniana . 



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