The structure of the monobarium salt of glucose 6-phosphate heptahydrate

Abstract is not available.

A simple procedure for purification of N-carbamoylputrescine: Application to assays of putrescine transcarbamoylase and agmatine iminohydrolase activities

The observation that N-carbamoylputrescine is quantitatively excluded on O-(carboxymethyl)-cellulose columns with simultaneous retention of putrescine and agmatine has been utilized to develop a sensitive radiometric assay for putrescine transcarbamoylase and a colorimetric assay for agmatine iminohydrolase. A simple procedure for obtaining bulk amounts of pure synthetic N-carbamoylputrescine by separation from putrescine and dicarbamoylputrescine on Dowex 50 (Na+) resin is described.

Behavior Of High-Voltage Machine Insulation System In The Presence Of Thermal And Electrical Stresses

This paper presents the results on a resin-rich machine insulation system subjected to varying stresses such as electrical (2.6 to 13.3 MV/m) and thermal (40 to 155° C) acting together. Accelerated electro-thermal aging experiments subsequently have been performed to understand the insulation degradation The interpretations are based on several measured properties like capacitance, loss tangent, ac resistance, leakage current, and partial discharge quantities. The results indicate that the changes in properties are not significant below a certain temperature for any applied stress, Beyond this temperature large variations are observed even for low electrical stresses. Electrothermal aging studies reveal that the acceleration of the insulation degradation and the ultimate time to failure depends on the relative values of temperature and voltage stresses. At lower temperatures, below critical, material characteristics of the system predominate whereas beyond this temperature, other phenomena come into play causing insulation deterioration. During aging under combined stresses, it appears that the prevailing temperature of the system has a significant role in the insulation degradation and ultimate failure.

Structure Of A Thionucleoside - 5'-Deoxy-5',6-Epithio-5,6-Dihydro-2',3'-Ortho-Isopropylidene-3-Methyluridine

C13HlsN205 S, M r = 314.35, orthorhombic, P212121 with a = 39.526 (4), b = 6.607 (2), c = 5.661 (2) A, Z = 4, V = 1478.36 A 3, D c = 1.412 Mg m -3, Cu Ka radiation. Final R = 0.073 for 1154 observed counter reflections. The sulphur atom is in a pseudo-equatorial position with respect to the dihydrouracil ring. The sugar pucker is predominantly O(l')-exo unlike the C(3')-exo,C(4')-endo observed for 2',3' O-isopropylideneuridine (ISPU). The fivemembered dioxolane ring has C(7) displaced by 0.497 (7)A from the best plane through atoms 0(2'), C(2'), C(3'), 0(3'), in contrast to ISPU where 0(3') shows the maximum deviation.

Effect of deprivation of vitamin A on the basic proteins of the nuclei of rat testes

The relative concentrations of the major histones, namely, H1, TH1, H2A, H2B, H3 and H4 are not significantly changed in the testes of the vitamin A-deficient rats, as compared to those in the normal controls. But the testis-specific protein, TP, which is synthesized at the mid-spermatid stage, is markedly reduced in the testes of the deficient rats. On supplementation of the deficient rats with retinyl acetate for 28 days, there was a 50% recovery in the relative concentration of the TP with respect to the total amounts of H1 and TH1.

The Structure Of 2',3'-O-Isopropylideneuridine

C12HI6N206 is orthorhombic, P2x2121, with a = 19.890 (5), b = 12.789 (2), c = 5.236 (1) A, Z = 4, U = 1331.9/~ 3, F(000) = 600. Mo Ka (/~ = 0.123 mm -1) intensities for 940 unique reflections up to sin 0/2 = 0.538/k -1 were collected on a CAD-4 diffractometer. Final R = 0.034. The glycosidic torsion angle 2~CN is 3"4 °, significantly smaller than that (56.5 °) in 2',3'- -methoxymethyleneuridine (MMU). The ribose moiety has a C(3')-exo-C(4')-endo twist conformation, in contrast to the C(2')-endo conformation in MMU. However, the maximum amplitudes of pucker for the ribose and dioxolane rings are very nearly the same for the two structures. The conformation about C(4')-C(5') is gauche-gauche (~0oo = -68-4, Ooc = 51.3°).

Separation of 5-methylcytosine-rich DNA using immobilized antibody

Anti-(5-methylcytosine) antibodies were immobilized on glutaraldehyde-activated Indion 48-R, a polystyrene resin with amino groups. Immobilized antibody was very stable and could be used several times without any apparent change in the initial binding capacity of the antibody-matrix. Fractions of total DNA from various animal and plant sources were retained on this column and could be eluted quantitatively with 1.0 m NaCl. The bound fraction was further characterized for its 5-methylcytosine content by restriction enzyme digestion patterns.

Structure of disodium guanosine 5'-phosphate heptahydrate

Abstract is not available.

Isonicotinic acid hydrazide - a reinvestigation

C6HvN30, orthorhombic, P2~2121, a = 14.915 (15), b=ll.400 (10), c=3.835 (5) A, Din= 1"417 (7), De= 1"395 g cm -3 and Z=4. The structure was refined by the least-squares method to an R of 0.072 for 699 observed reflexions. The angle between the mean planes of the pyridine ring and the acid hydrazide moiety is 18.1 °. The molecules are held together in the crystal by a network of N-H...N hydrogen bonds.

Molecular and crystal structure of deoxyguanosine 5'-phosphate

RECENT crystallographic studies of the dinucleosides ApU (ref. 1) and GpC (ref. 2) have given experimental proof for the base pairing arrangement proposed by Watson and Crick for the DNA double helix3. Another striking feature of this structure relates to the torsional angle about the C5'-C4' bond in the phosphate−sugar backbone chain. In the Crick and Watson model4, this conformation is gauche−trans (GT). Crystal structures of 5'-nucleotides, dinucleosides and dinucleotides so far studied, however, have shown only the gauche−gauche (GG) conformation about this bond. The GG conformer is also the only one found in the refined models of the proposed structure of the double helical nucleic acids and polynucleotides5−7. The only nucleotide with a GT conformation is 6-azauridine-5'-phosphate8 which is not a normal monomer unit of nucleic acids. It is also reported that 5'-dGMP assumes preferentially GT conformation in solution9.

The structure of the monobarium salt of glucose 6-phosphate heptahydrate

C6H11o9P2-.Ba2+.7H2o, M, = 521.5, is monoclinic, space group P21, a = 11.881 (4), b = 8.616 (5), c = 8.350 (4) A,B = 102.95 (3)0, Z = 2, U = 833.0 A 3, d m = 2.09, d c = 2.08 Mg m -3, F(000) = 516. Mo Ka (u = 0.034 mm -1) intensity data. R is 0.068 for 1603 reflections. Of the two endocyclic C-O bonds in the glucose ring, C(5)-O(5) [1.463 (23)] is longer than C(1)-O(5) [1.395 (23)A]. The pyranose sugar ring takes a 4C1 chair conformation. The Cremer-Pople puckering parameters are, 0 = 6.69 o, Q = 0.619 A and 0 = 263.7o. The conformation about the exocyclic C(5)-C(6) bond is gauche-gauche, in contrast to gauche-trans observed in the structure of glucose 1-phosphate. The phosphate ester bond, P-O(6), is 1.61 (1)A. It is similar in length to the 'high-energy' P~O bond in phosphoenolpyruvate. The Ba 2÷ ion is surrounded by nine O atoms within a distance of 2.95 A, of which seven are from water molecules. There is an intramolecular hydrogen bond between the sugar hydroxyl 0(4) and phosphate oxygen O(12).

Molecular and crystal structure of deoxyguanosine 5'-phosphate

RECENT crystallographic studies of the dinucleosides ApU (ref. 1) and GpC (ref. 2) have given experimental proof for the base pairing arrangement proposed by Watson and Crick for the DNA double helix3. Another striking feature of this structure relates to the torsional angle about the C5'-C4' bond in the phosphate−sugar backbone chain. In the Crick and Watson model4, this conformation is gauche−trans (GT). Crystal structures of 5'-nucleotides, dinucleosides and dinucleotides so far studied, however, have shown only the gauche−gauche (GG) conformation about this bond. The GG conformer is also the only one found in the refined models of the proposed structure of the double helical nucleic acids and polynucleotides5−7. The only nucleotide with a GT conformation is 6-azauridine-5'-phosphate8 which is not a normal monomer unit of nucleic acids. It is also reported that 5'-dGMP assumes preferentially GT conformation in solution9.

Structural Crystallography and Crystal Chemistry

Abstract is not available.

Polymer supported metal complexes as catalysts for oxidation of thiosalts by molecular oxygen IV. Quaternised poly(4-vinyl pyridine) complexes with Cu2+ as template

Copper(II) complexes of quaternised poly(4-vinylpyridine) (PVP) of different degrees of quaternisation and copper content have been prepared by crosslinking the polymer with 1,2-dibromoethane in the presence of Cu2+ ion as template. The stability constant of the PVP---Cu(II) complexes is found to increase with the degree of crosslinking quaternisation of the resin, but the rate at which Cu2+ is adsorbed by the resin decreases. An optimum combination of both stability and rate can be achieved with a moderate degree (31%) of crosslinking. A kinetic study reveals that quaternisation increases significantly the catalytic activity of the complex for the oxidation of S2O2−3 by O2 compared with PVP----Cu(II) without quaternisation, but it deactivates the complex for the oxidation of both S3O2−6 and S4O2−6. The batch reactor oxidation kinetics at pH 2.16, where the rate is observed to be maximum, is well explained by the Langmuir—Hinshelwood model assuming the coordination of both O2 and thioanion to Cu(II) as a precursor to the oxidation reaction.