Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.8 (polynucleotide phosphorylase)
 723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

O2-Ethyl-UDP and O4-methyl-UDP have been prepared and copolymerized in various proportions with UDP or CDP, using polynucleotide phosphorylase. The copolymers were used as templates for DNA-dependent RNA polymerases in the presence of Mn2+. Both of the O-alkylated uridines caused a similar misincorporations. When copolymerized with U they led to incorporation of CMP and GMP into the poly(A). No AMP or UMP incorporation seemed to be caused by the introduction of O-alkyluridines into either poly(U) or poly(C). The mispairing of O2- and O4-alkyluridine to behave like C or G represents mutagenic events. O2 alkylation of U or T is, in contrast to O4 alkylation, a relatively frequent result of treatment of double-stranded nucleic acids with N-nitroso alkylating agents. In single-stranded nucleic acids both O2 and O4 alkylations of U and T occur to similar extents. Thus, the observed mutagenic effects of O2 and O4 alkylation of U may be involved in the high carcinogenicity of these alkylating agents.
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PMID:Preparation and template activities of polynucleotides containing O2- and O4-alkyluridine. 27 2

Homopolymers of etheno CMP have been prepared by the action of polyribonucleotide phosphorylase upon etheno CDP. At alkaline pH the optical properties are consistent with a structure consisting of partially helical single-stranded chains whose helical regions are stabilized by base stacking. At acid pH the degree of helicity increases markedly. The degree of cooperativity displayed by the helix leads to coil transition induced by pH or temperature is less than for the case of polyribocytidylic acid. In the presence of acridine orange the alkaline form develops a strong extrinsic CD spectrum.
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PMID:Physical properties of poly (3,N4-ethenocytidylic acid). 62 74

The platelet population of man and rat can be divided into two classes of about equal size on the basis of presence/absence of an acid phosphatase which acts on para-nitrophenylphosphate (a PNPase), at pH 5. The cytochemical reaction product is in the platelet cytoplasmic matrix, without apparent association with organelles or membrane systems. We could not relate differences in staining to differences in function: all cells responded the same to activation by thrombin, ADP, or collagen, in fibrinogen binding to activated platelets, by endocytosis of fluid-phase tracers, and in internalization of latex particles. With respect to possible physiological substrates for the PNP-ase, there was no reaction product from beta-glycerophosphate, AMP, ADP, ATP, GTP, CMP, IMP, cAMP, creatine phosphate, and inositol phosphates, and the enzyme was not inhibited by 40 mM lithium. There was reaction product from tyrosine phosphate suggesting that the physiological substrate for PNP-ase is tyrosine phosphate. In rat bone marrow, megakaryocytes also were of two classes, PNPase positive and PNPase negative, suggesting that different classes of platelets arise from different classes of megakaryocytes.
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PMID:Blood platelet heterogeneity: evidence for two classes of platelets in man and rat. 752 21