KARASEK ET Ah. 113 



Thus, carbobenzoxytryptophanyl adenylate, 3 _a l an yl adenylate, and benzoyl 

 adenylate were inactive (table 1). Table 2 summarizes some of the reactions 

 catalyzed by the tryptophan-activating enzyme preparation. Under the condi- 

 tions employed, the enzyme catalyzed the formation of L-tryptophan hydroxa- 

 mate, but not that of the d isomer. This is in striking contrast to the results ob- 

 tained on the synthesis of adenosine triphosphate (table 1). Further studies of 

 the specificity of the enzyme system are in progress. 



TABLE 1. Specificity of the Tryptophan-Activating Enzyme with Respect to Acyl 

 Adenylate in Synthesis of Adenosine Triphosphate 



Acyl Adenylates 



A . 



I \ \ 



Active Inactive 



L-Tryptophan-AMP 3-Alanine-AMP 



D-Tryptophan-AMP Acetyl-AMP 



L-Phenylalanine-AMP Benzoyl-AMP 



D-Phenylalanine-AMP Carbobenzoxytryptophan-AMP 



L-Glutamine-AMP Phenylacetyl-AMP 



L-Isoleucine-AMP 

 L-Leucine-AMP 

 L-Valine-AMP 

 L-Alanine-AMP 

 L-Tyrosine-AMP 

 Glycine-AMP 

 L-Proline-AMP 

 L-Threonine-AMP 

 L-Serine-AMP 



TABLE 2. Types of Reactions Catalyzed by Tryptophan-Activating Enzyme 



Specificity 



+ 



D 

 



+ 







+ 



Note Added in Proof 



Novelli [Proc. Natl. Acad. Set. U. S. t 44, 86 (1958)] has very recently reported 

 synthesis of adenosine triphosphate from pyrophosphate and several aminoacyl 

 adenylates with this enzyme, and Berg {Federation Proc., 16, 152 (1957) ; per- 

 sonal communication] has made similar observations with a methionine-acti- 

 vating enzyme obtained from yeast. Rhodes and McElroy (personal communi- 

 cation) have recently observed enzymatic synthesis of adenyl oxyluciferin by 



