Phosphorolytic Cleavage (phosphorolytic + cleavage)

Distribution by Scientific Domains

Selected Abstracts

Sucrose phosphorylase of the rumen bacterium Pseudobutyrivibrio ruminis strain A

A. Kasperowicz
Abstract Aims:, To verify the taxonomic affiliation of bacterium Butyrivibrio fibrisolvens strain A from our collection and to characterize its enzyme(s) responsible for digestion of sucrose. Methods and Results:, Comparison of the 16S rRNA gene of the bacterium with GenBank showed over 99% sequence identity to the species Pseudobutyrivibrio ruminis. Molecular filtration, native electrophoresis on polyacrylamide gel, zymography and thin layer chromatography were used to identify and characterize the relevant enzyme. An intracellular sucrose phosphorylase with an approximate molecular mass of 52 kDa exhibiting maximum activity at pH 60 and temperature 45C was identified. The enzyme was of inducible character and catalysed the reversible conversion of sucrose to fructose and glucose-1-P. The reaction required inorganic phosphate. The Km for glucose-1-P formation and fructose release were 388 10,3 and 556 10,3 mol l,1 sucrose, respectively , while the Vmax of the reactions were ,0579 and 09 ,mol mg protein,1 min,1. The enzyme also released free glucose from glucose phosphate. Conclusion:,Pseudobutyrivibrio ruminis strain A utilized sucrose by phosphorolytic cleavage. Significance and Impact of the Study:, Bacterium P. ruminis strain A probably participates in the transfer of energy from dietetary sucrose to the host animal. [source]

Structure of Escherichia coli uridine phosphorylase at 2.0,

F. Temple Burling
The 2.0, crystal structure has been determined for Escherichia coli uridine phosphorylase (UP), an essential enzyme in nucleotide biosynthesis that catalyzes the phosphorolytic cleavage of the C,N glycosidic bond of uridine to ribose-1-phosphate and uracil. The structure determination of two independent monomers in the asymmetric unit revealed the residue composition and atomic details of the apo configurations of each active site. The native hexameric UP enzyme was revealed by applying threefold crystallographic symmetry to the contents of the asymmetric unit. The 2.0, model reveals a closer structural relationship to other nucleotide phosphorylase enzymes than was previously appreciated. [source]

Crystallization and preliminary X-ray diffraction analysis of Salmonella typhimurium uridine phosphorylase complexed with 5-fluorouracil

A. A. Lashkov
Uridine phosphorylase (UPh; EC catalyzes the phosphorolytic cleavage of the N-glycosidic bond of uridine to form ribose 1-phosphate and uracil. This enzyme also activates pyrimidine-containing drugs, including 5-fluorouracil (5-FU). In order to better understand the mechanism of the enzyme,drug interaction, the complex of Salmonella typhimurium UPh with 5-FU was cocrystallized using the hanging-drop vapour-diffusion method at 294,K. X-ray diffraction data were collected to 2.2, resolution. Analysis of these data revealed that the crystal belonged to space group C2, with unit-cell parameters a = 158.26, b = 93.04, c = 149.87,, , = , = 90, , = 90.65. The solvent content was 45.85% assuming the presence of six hexameric molecules of the complex in the unit cell. [source]

Preliminary investigation of the three-dimensional structure of Salmonella typhimurium uridine phosphorylase in the crystalline state

Olga K. Molchan
Uridine phosphorylase (UPh) catalyzes the phosphorolytic cleavage of the C,N glycosidic bond of uridine to ribose 1-phosphate and uracil in the pyrimidine-salvage pathway. The crystal structure of the Salmonella typhimurium uridine phosphorylase (StUPh) has been determined at 2.5, resolution and refined to an R factor of 22.1% and an Rfree of 27.9%. The hexameric StUPh displays 32 point-group symmetry and utilizes both twofold and threefold non-crystallographic axes. A phosphate is bound at the active site and forms hydrogen bonds to Arg91, Arg30, Thr94 and Gly26 of one monomer and Arg48 of an adjacent monomer. The hexameric StUPh model reveals a close structural relationship to Escherichia coli uridine phosphorylase (EcUPh). [source]