26 



concentrations of 1.0 mM NADPH and 1.0 mM DHS or at 

 concentrations otherwise stated. 



Ouinate dehydrogenase . Quinate dehydrogenase was 

 assayed with 1.0 mM quinate and 1.0 mAf NAD* or NADP* in 100 

 mM glycine buffer at pH 9.5. 

 Prephenate dehydratase 



Prephenate dehydratase was assayed by incubation of PPA 

 and enzyme in 50 mM EPPS buffer (total vol of 100 ^1) at 

 37°C for 10 to 20 min before addition of 100 fil IN HCl 

 followed by further incubation at 37°C for 10 min. Controls 

 included PPA or enzyme with buffer only. Activity was 

 calculated from spectrophotometric readings at A320 nm arid an 

 extinction coefficient of 17,500. 

 Protein estimations 



Protein concentrations were estimated by the method of 

 Bradford (14) with BSA as a standard. A micro-assay was 

 used, as described, to estimate highly purified protein 

 concentrations . 

 Definition of activity and specific activity 



Activity for all enzyme reactions in this study are 

 defined as nmol min"^ for the stated amount of protein added 

 into a standard assay volume. Specific activity is defined 

 as nmol min'^ mg protein'^. 



