Glycinamide ribonucleotide, structure

Schmitt, E., Blanquet, S., and Mechulam, Y. (1996). Structure of crystalline Escherichia colt methionyl-tRNA(f)Met formyltransferase comparison with glycinamide ribonucleotide formyltransferase. EMBO J., 15, 4749-4758. 

Wang, W., Kappock, T. J., Stubbe, J., and Ealick, S. E. (1998). X-ray crystal structure of glycinamide ribonucleotide synthetase from Escherichia coli. Biochemistry, 37, 15647-15662. 

Fig. 9.8. a) Structural overlay of glycinamide ribonucleotide transformylase (PurN) [155] and the N-terminal domain of tRNA(fMet)-formyl-transferase (FMT) [156] from E. coli. Despite the low sequence identity (33 %), the two structures are almost perfectly superimposable. b) Structure-based multiple sequence alignment of PurN... 

J.B. Thoden, S. Firestine, A. Nixon, S. J. Benkovic, and H.M. Holden. 2000. Molecular structure of Escherichia coli PurT-encoded glycinamide ribonucleotide transformylase Biochemistry 39 8791-8802. (PubMed)... 

The possibility that the iV °-formyl derivative (III.163) might serve as a substrate for two important enzymes of the de novo purine pathway that utilize reduced folates as their natural substrates, namely 5-aminoimidazole-4-car-boxamide ribonucleotide (AICAR) transformylase and glycinamide ribonucleotide (GAR) transformylase, was examined [61]. While the affinity of (III. 163) (AT, (app) = 29/xM) for AICAR transformylase appeared to be greater than that of the natural substrate 10-formyltetrahydrofolate (A (app) = 68 /xM), the reaction was slow, resulting in a 750-fold lower Frei/Am(app) ratio for the quinazoline. The affinity of (III. 163) (/frn(app) = 1.9 /xM) for GAR transformylase was likewise several times greater than that of the natural substrate, in this case 5,10-methenyltetra-hydrofolate (/if,n(app) = 8.9/xM). However, (III. 163) was also used rather efficiently in the reaction by GAR transformylase, resulting in a 4-fold higher V.J Ai, (app) for the quinazoline than for 5,10-methenyltetrahydrofolate. The authors concluded from these results that the 5,10-methenyl structure is not needed for GAR transformylase activity. 

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