Publications

• Identification of Rv0535 as methylthioadenosine phosphorylase from Mycobacterium tuberculosis.

  Buckoreelall K., Sun Y., Hobrath J.V., Wilson L., Parker W.B.

  5'-methylthioadenosine (MTA) is a natural purine that is metabolized by methylthioadenosine phosphorylase (MTAP, E.C 2.4.2.28) in Eukarya and Archaea but generally not in bacteria. In this work, Rv0535, which has been annotated as a probable MTAP in Mycobacterium tuberculosis, was expressed in and ... >> More

  5'-methylthioadenosine (MTA) is a natural purine that is metabolized by methylthioadenosine phosphorylase (MTAP, E.C 2.4.2.28) in Eukarya and Archaea but generally not in bacteria. In this work, Rv0535, which has been annotated as a probable MTAP in Mycobacterium tuberculosis, was expressed in and purified from Escherichia coli BL21 (DE3). The purified protein displayed properties of a phosphorylase and MTA was the preferred substrate. Adenosine and S-adenosyl-l-homocysteine were poor substrates and no activity was detected with 5'-methylthioinosine, the other natural purines, or the natural pyrimidines. Kinetic analysis of M. tuberculosis MTAP showed that the K(m) value for MTA was 9 μM. Rv0535 was estimated as a 30 kDa protein on a denaturing SDS-PAGE gel, which agreed with the molecular mass predicted by its gene sequence. Using gel filtration chromatography, the native molecular mass of the enzyme was determined to be 60 ± 4 kDa, and thus indicated that M. tuberculosis MTAP is a dimer. Differences in active site between mycobacterial and human MTAPs were identified by homology modeling based on the crystal of the human enzyme. A complete structure-activity relationship analysis could identify differences in substrate specificity between the two enzymes to aid in the development of purine-based, anti-tuberculosis drugs. << Less

  Tuberculosis 92:139-147(2012) [PubMed] [EuropePMC]

• 5'-Methylthioadenosine phosphorylase from Caldariella acidophila. Purification and properties.

  Carteni'-Farina M., Oliva A., Romeo G., Napolitano G., De Rosa M., Gambacorta A., Zappia V.

  The occurrence of 5'-methylthioadenosine phosphorylase in Caldariella acidophila, a thermophilic bacterium growing optimally at 87 degrees C, is reported. It represents the first example in prokaryotes of a phosphoryolytic cleavage of the thioether. The reaction products, purified by ion-exchange ... >> More

  The occurrence of 5'-methylthioadenosine phosphorylase in Caldariella acidophila, a thermophilic bacterium growing optimally at 87 degrees C, is reported. It represents the first example in prokaryotes of a phosphoryolytic cleavage of the thioether. The reaction products, purified by ion-exchange chromatography, have been identified as 5-methylthioribose-1-phosphate and adenine by several analytical procedures. The enzyme has been purified to homogeneity in 32% yield by using DEAE-cellulose and hydroxyapatite chromatography, gel filtration and isoelectric focusing. The enzyme shows a high degree of thermophilicity, its temperature optimum being at 93 degrees C; furthermore no loss of activity is observable after exposure for 1 h at 100 degrees C. The kinetic data indicate a sequential mechanism of the reaction. The apparent Km values are 0.095 mM for 5'-methylthioadenosine and 6.1 mM for phosphate. The specificity of the reaction is rather strict. Experiments performed with analogues of the substrate, i.e. 5'-methylthioinosine, 5'-dimethylthioadenosine sulfonium salt, 5'-n-butylthioadenosine, 5'-isobutylthioadenosine, 5'-isobutylthioinosine, adenosylhomocysteine, 5'-thioethanoladenosine, adenosine, indicate the relevance of the adenine amino group and the sulfur in thioether form in the binding to the enzyme protein. << Less

  Eur J Biochem 101:317-324(1979) [PubMed] [EuropePMC]

• Demonstration of 5'-methylthioadenosine phosphorylase activity in various rat tissues. Some properties of the enzyme from rat lung.

  Garbers D.L.

  An enzyme (5'-methylthioadenosine phosphorylase) that catalyzes the phosphorolytic cleavage of 5'-methylthioadenosine to 5-methylthioadenosine to 5-methylthioribose-1-phosphate and adenine was found in various rat tissues. Liver and lung had the highest enzyme activities and heart the lowest, most ... >> More

  An enzyme (5'-methylthioadenosine phosphorylase) that catalyzes the phosphorolytic cleavage of 5'-methylthioadenosine to 5-methylthioadenosine to 5-methylthioribose-1-phosphate and adenine was found in various rat tissues. Liver and lung had the highest enzyme activities and heart the lowest, most of the activity (greater than 90%) was recovered in soluble tissue fractions. The enzyme from rat lung was purified about 30-fold by pH treatment (NH4)2SO4 fractionation, and gel filtration. The enzyme did not require an added metal-ion for activity, and was not inhibited by EDTA. Many compounds were tested for their inhibitory effects; of these, ribose 1-phosphate, 2-deoxyribose 1-phosphate, fructose 1-phosphate, adenine and guanine were shown to inhibit. Kinetic patterns on reciprocal plots were linear as a function of the concentration of either 5'-methylthioadenosine or phosphate. More detailed kinetic studies suggested that the rat lung 5'-methylioadenosine phosphorylase catalyzes an equilibrium-ordered reaction, and that 5'-methylthioadenosine is the first substrate to bind and 5-methylthioribose-1-phosphate is the first product to be released. << Less

  Biochim Biophys Acta 523:82-93(1978) [PubMed] [EuropePMC]

• Phosphate-stimulated breakdown of 5'-methylthioadenosine by rat ventral prostate.

  Pegg A.E., Williams-Ashman H.G.

  A soluble enzyme preparation catalysing the release of adenine from 5'-methylthioadenosine was purified some 30-fold from extracts of the rat ventral prostate. This reaction was completely dependent on addition of inorganic phosphate ions to the assay medium. This absolute requirement for phosphat ... >> More

  A soluble enzyme preparation catalysing the release of adenine from 5'-methylthioadenosine was purified some 30-fold from extracts of the rat ventral prostate. This reaction was completely dependent on addition of inorganic phosphate ions to the assay medium. This absolute requirement for phosphate ions suggests a phosphorolytic cleavage mechanism. After acid treatment, the other product of the reaction appeared to be 5-methylthioribose. The actions of some other well-characterized enzymes of nucleoside metabolism of 5'-methylthioadenosine were also investigated; purified purine nucleoside phosphorylases from calf spleen and human erythrocytes did not attack 5'-methylthioadenosine. The role of 5'-methylthioadenosine in mammalian tissues is discussed. << Less

  Biochem J 115:241-247(1969) [PubMed] [EuropePMC]