Oligomeric structure of mammalian purine nucleoside phosphorylase in solution determined by analytical ultracentrifugation.

The influence of phosphate, ionic strength, temperature and enzyme concentration on the oligomeric structure of calf spleen purine nucleoside phosphorylase (PNP) in solution was studied by analytical ultracentrifugation methods. Sedimentation equilibrium analysis used to directly determine the enzyme molecular mass revealed a trimeric molecule with Mr = (90.6 +/- 2.

Crystal structure of calf spleen purine nucleoside phosphorylase with two full trimers in the asymmetric unit: important implications for the mechanism of catalysis.

The crystal structure of the binary complex of trimeric purine nucleoside phosphorylase (PNP) from calf spleen with the acyclic nucleoside phosphonate inhibitor 2,6-diamino-(S)-9-[2-(phosphonomethoxy)propyl]purine ((S)-PMPDAP) is determined at 2.3A resolution in space group P2(1)2(1)2(1). Crystallization in this space group, which is observed for the first time with a calf spleen PNP crystal structure, is obtained in the presence of calcium atoms.

Calf spleen purine-nucleoside phosphorylase: crystal structure of the binary complex with a potent multisubstrate analogue inhibitor.

Purine-nucleoside phosphorylase (PNP) deficiency in humans leads to inhibition of the T-cell response. Potent membrane-permeable inhibitors of this enzyme are therefore considered to be potential immunosuppressive agents. The binary complex of the trimeric calf spleen phosphorylase, which is highly homologous to human PNP, with the potent ground-state analogue inhibitor 9-(5,5-difluoro-5-phosphonopentyl)guanine (DFPP-G) was crystallized in the cubic space group P2(1)3, with unit-cell parameter a = 93.

Crystal structure of calf spleen purine nucleoside phosphorylase in a complex with multisubstrate analogue inhibitor with 2,6-diaminopurine aglycone.

The crystal structure at 2.05 A resolution of calf spleen PNP complexed with stoichiometric concentration of acyclic nucleoside phosphonate inhibitor, 2,6-diamino-(S)-9-[2-(phosphonomethoxy)propyl]purine, in a new space group P2(1)2(1)2(1) which contains two full trimers in the asymmetric crystal unit is described.

Interactions of trimeric purine nucleoside phosphorylases with ground state analogues--calorimetric and fluorimetric studies.

Binding enthalpies, dissociation constants and stoichiometry of binding for interaction of trimeric calf spleen and Cellulomonas sp. purine nucleoside phosphorylases with their ground state analogues (substrates and inhibitors) were studied by calorimetric and spectrofluorimetric methods. Data for all ligands, with possible exception of hypoxanthine, are consistent with three identical non-interacting binding sites.