Metabolism of 6-Mercaptopurine by Resistant Escherichia coli Cells1
AUTOR(ES)
Coggin, Joseph H.
RESUMO
Coggin, Joseph H. (University of Chicago, Chicago, Ill.), Muriel Loosemore, and William R. Martin. Metabolism of 6-mercaptopurine by resistant Escherichia coli cells. J. Bacteriol. 92:446–454. 1966.—6-Mercaptopurine (MP) utilization as a source of purine in MP-sensitive and -resistant cultures of Escherichia coli was investigated. The label of MP-8-C14 appeared in adenine and guanine of ribonucleic acid and deoxyribonucleic acid in sensitive and resistant cultures. Studies using MP-S35 further demonstrated that the MP moiety was degraded, as shown by a rapid decrease in radioactivity from cells upon exposure to MP for 20 min. Enzymatic analysis showed that MP was converted to 6-mercaptopurine ribonucleotide (MPRP) by extracts derived from both sensitive and resistant cells. Resistant cell preparations, however, degraded MPRP to inosine monophosphate (IMP) rapidly when compared with analogue degradation by sensitive cells. Inosineguanosine-5′-phosphate pyrophosphorylase from resistant cells did not catalyze the synthesis of IMP from hypoxanthine when the cells were cultured in the presence of MP, but these enzyme preparations actively converted guanine to guanosine monophosphate (GMP). Pyrophosphorylase derived from resistant cells cultured in medium without MP catalyzed the conversion of hypoxanthine to IMP and also guanine to GMP. These observations suggest that inosine-guanosine-5′-phosphate pyrophosphorylase is composed of two distinct enzymes. The mode of resistance to MP in E. coli is related to an enhancement of the enzymatic degradation of MPRP to the pivotal purine intermediate, IMP.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=276262Documentos Relacionados
- Comparative Study of 6-Mercaptopurine Metabolism in Human Leukemic Leukocytes and L1210 Cells
- Inhibition by 6-Mercaptopurine of Polyarthritis induced by Freund's Adjuvant
- Effect of 6-Mercaptopurine on Endotoxin Tolerance*
- Immunosuppressive Effect of 6-Mercaptopurine and Mitomycin C
- THE EFFECTS OF 6-MERCAPTOPURINE ON HOMOGRAFT REACTIONS *