35. BIOSYNTHESIS OF PURINE NUCLEOTIDES 



307 



° 5POC ^o.r 



/Ol H> 



h V- — Toh 



OH OH 

 RIB0SE-5-PH0SPHATE 



GLUTAMINE 6LUTAMATE 

 +H,0 +HP ? 0^ 



GLYCINE 

 + ATP ADP + HPQ 



*9+ 



HPO 



aB h/\ , j„f + • /Ch H7\ 

 h V— - r op.o; "• h V— -f t 



OH OH OH OH 



5-PHOSPHORIBOSYLPYROPHOSPHATE 5-PHOSPHORIBOSYLAMINE 



Oj or C0 2 



0\ POCH 2 \ 



CH 



ADP+HPO: ATP 



H^i 



N . H GLUTAMATE GWTAMINE 

 \ +AOP+HPQ: +ATP+H.0 

 CHO 



ICltf* ^V-TH 



OH OH 

 F0RMYL6LYCINAMIDINE RIBOTIDE 



COO 



HC-N-C 

 COO N C— N 

 ^ ASPARTATE A OP // \ 



HjN-C CH +ATP +HPO4 H 2 N-C CH 



' o;poch, H y 



H I - 1 H 

 OH OH 



OH OH 

 AMINOIMIDAZOLE RIBOTIDE 



C — N 



N 5 ,N 10 - 

 ANHYDROFORMYL- 

 FH4 

 + H 2 



°^>0./ 



OH OH 

 FORMYLGLYCINAMIDE RIBOTIDE 



H^tMTh 

 OH OH 



H 2 N^ 

 FUMARATE 



/ . H 2 N 



/ o;poch. 



Mg< 



\ 



C — N 



// W 



• C CH 



X N^ 



\^0\/ 



hT^h 



OH OH 



5-AMIN0-4-IMIDAZ0LECARB0XYLIC 

 ACID RIBOTIDE 



5-AMIN0-4-IMIDAZ0LE-N-SUCCIN0- 5-AUIN0-4- IMIDAZOLE - 



CARBOXAMIDE RIBOTIDE 



HN 

 / 

 HC 



CARBOXAMIDE RIBOTIDE 



; 



_c 



\ 



IH-C. 



-N 



0;POCH. 



\\ 



N C CH 



H,0 



OHC. 



m 



\, 



O'jPOCHjS/O-x./ 



QH OH 

 INOSINIC ACID 



£*i 



N' -FORMYL-FH 4 



OH OH 



5-F0RMAMIDO-4-IMIDAZ0LECARBOXAMIDE 

 RIBOTIDE 



Fig. 2. Enzymic synthesis of inosinic acid de novo. 



tives which are able to undergo diazotization and coupling with N-l- 

 naphthylethylenediamine according to the procedure of Bratton and Mar- 

 shall' 24 to yield colored products with characteristic absorption spectra. 

 These circumstances have permitted the identification and different ation 

 of these cyclic intermediates. These heterocyclic intermediates may also 

 be distinguished as a group from such arylamines as p-aminobenzoic acid 

 by virtue of the fact that they are not readily acetylated by acetic anhy- 

 dride whereas the carbocyclic amines are. 25 The compounds and reactions 

 concerned with the synthesis of inosinic acid from its precursors are shown 

 in Fig. 2, and the reactions for the synthesis of guanylic and adenylic acids 

 from inosinic acid are shown in Fig. 3. 



24 A. C. Bratton and E. K. Marshall, Jr., J. Biol. Chem. 128, 537 (1939). 



25 J. M. Ravel, R. E. Eakin, and W. Shive, /. Biol. Chem. 172, 67 (1948). 



