Results 181 to 190 of about 27,209 (247)

Purine Nucleoside Phosphorylase. 2. Catalytic Mechanism

Biochemistry, 1997
X-ray crystallography, molecular modeling, and site-directed mutagenesis were used to delineate the catalytic mechanism of purine nucleoside phosphorylase (PNP). PNP catalyzes the reversible phosphorolysis of purine nucleosides to the corresponding purine base and ribose 1-phosphate using a substrate-assisted catalytic mechanism.
M D, Erion, J D, Stoeckler, W C, Guida, R L, Walter, S E, Ealick   +4 more
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Purine nucleoside phosphorylase from bovine liver

Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1978
1. Purine nucleoside phosphorylase (purine nucleoside:orthophosphate ribosyltransferase, E.C. 2.4.2.1) from liver of cattle, Bos taurus, was purified to homogeneity. Some properties of the enzymes from three different bovine tissues were compared and discussed. 2.
Z, Ikezawa, T, Nishino, K, Murakami, K, Tsushima   +3 more
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Mutations in purine nucleoside phosphorylase deficiency

Human Mutation, 1997
Purine nucleoside phosphorylase deficiency is an inherited disease of purine metabolism characterized clinically as combined immunodeficiency. The molecular defects have been published for 4 different alleles in 3 patients. We report four new mutations including two amino acid substitutions, A174P and G190V, a single codon deletion, delta I129, and a ...
M L, Markert, B D, Finkel, T M, McLaughlin, T J, Watson, H R, Collard, C P, McMahon, L G, Andrews, M J, Barrett, F E, Ward   +8 more
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Allosteric regulation of purine nucleoside phosphorylase

Archives of Biochemistry and Biophysics, 1991
Purine nucleoside phosphorylase (EC 2.4.2.1) from bovine spleen is allosterically regulated. With the substrate inosine the enzyme displayed complex kinetics: positive cooperativity vs inosine when this substrate was close to physiological concentrations, negative cooperativity at inosine concentrations greater than 60 microM, and substrate inhibition ...
P A, Ropp, T W, Traut
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Stroke in purine nucleoside phosphorylase deficiency

Pediatric Neurology, 1995
The first documented case of cerebrovascular disease occurring in a 13-year-old girl with purine nucleoside phosphorylase deficiency is reported. This patient, the oldest known survivor with purine nucleoside phosphorylase deficiency, had previously experienced multiple sequential neurologic problems.
D A, Tam, R T, Leshner
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Prenatal exclusion of purine nucleoside phosphorylase deficiency

European Journal of Pediatrics, 1986
We report on the prenatal exclusion of purine nucleoside phosphorylase (PNP) deficiency in a fetus whose parents were known to be heterozygotes for the enzyme defect. Prenatal investigation was performed in the 16th week of gestation on amniotic fluid and cultured amnion cells using sensitive techniques.
E. Carapella De Luca, STEGAGNO, MICHELE, C. Dionisi Vici, PAESANO, Rosalba, L. D. Fairbanks, G. S. Morris, H. A. Simmonds   +6 more
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Adenine as Substrate for Purine Nucleoside Phosphorylase

Canadian Journal of Biochemistry, 1971
Purine nucleoside phosphorylase (purine-nucleoside:orthophosphate ribosyltransferase, EC 2.4.2.1) from four sources (rat liver and brain, human erythrocytes, and calf spleen) has been shown to exhibit a low intrinsic activity towards adenine in the presence of ribose 1-phosphate.
T P, Zimmerman, N B, Gersten, A F, Ross, R P, Miech   +3 more
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Characterization of purine nucleoside phosphorylase in leukemia

American Journal of Hematology, 1986
AbstractPurine nucleoside phosphorylase (PNP) activity was determined in mononuclear cells from 49 patients with various types of leukemia. A low level of PNP activity was found in mononuclear cells from patients with acute myeloid and lymphoblastic leukemia and with chronic lymphocytic leukemia. Enzymatic and immunological studies on PNP from leukemic
T, Morisaki, N, Horiuchi, H, Fujii, S, Miwa   +3 more
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Purine Nucleoside Phosphorylase. 1. Structure−Function Studies

Biochemistry, 1997
To probe the catalytic mechanism of human purine nucleoside phosphorylase (PNP), 13 active-site mutants were constructed and characterized by steady-state kinetics. In addition, microtiter plate assays were developed for both the phosphorolytic and synthetic reactions and used to determine the kinetic parameters of each mutant.
M D, Erion, K, Takabayashi, H B, Smith, J, Kessi, S, Wagner, S, Hönger, S L, Shames, S E, Ealick   +7 more
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[Purine nucleoside phosphorylase (PNP)].

Nihon rinsho. Japanese journal of clinical medicine, 1997
PNP, encoded by 6 exons on human chromosome 14q13, is a homotrimetic enzyme of approximately 96 k dalton. This enzyme reversibly catalyzes the phosphorolysis of purine nucleoside to their respective purine bases and the corresponding pentose-1-phosphate.
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