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1.
J Chromatogr A ; 914(1-2): 147-59, 2001 Apr 20.
Article in English | MEDLINE | ID: mdl-11358208

ABSTRACT

HPLC and gel permeation chromatographic (GPC) characterization of complex phenol-formaldehyde resins is described. Reversed-phase HPLC fingerprints the phenolic monomers, dimers and some oligomers. The molecular masses of these phenolic compounds were determined using an ion trap mass spectrometer. GPC analyzes tetrahydrofuran-soluble phenolic polymers beyond HPLC capability. The molecular mass distribution and structural information of the phenolics was determined by both conventional and laser light-scattering calibration methods. GPC with both UV and refractive index detection provides weight concentration of phenolic resin and the molar concentration of the phenol unit in the oligomers or polymers.


Subject(s)
Chromatography, Gel/methods , Chromatography, High Pressure Liquid/methods , Phenols/isolation & purification , Spectrum Analysis/methods , Molecular Weight , Phenols/chemistry
2.
J Biol Chem ; 260(12): 7562-7, 1985 Jun 25.
Article in English | MEDLINE | ID: mdl-3997888

ABSTRACT

Phosphocreatinine undergoes the following spontaneous simultaneous reactions at pH 7.4 (0.02 M sodium phosphate and 120 mM KCl) and 38 degrees C. (Formula: see text) The first order rate constants are 0.046 h-1 (ka) and 0.048 h-1 (kb). There is a major effect of pH on the reactions such that at pH values higher than 7.4 phosphocreatine production predominates, while at pH values less than 7.4 creatinine is the major product. This along with titration data showing apparent pK values of about 3.0 and 7.5 for phosphocreatinine suggest that the dianionic form of phosphocreatinine is involved in the conversion to phosphocreatine, whereas the monoanionic form is exclusively converted to creatinine. Possible mechanisms to account for the reactivity of phosphocreatinine are discussed. Several lines of evidence suggest that the apparent Keq for phosphocreatine formation from phosphocreatinine is about 300 at pH 9.0 and about 70 at pH 7.0, and the delta G0' (pH 7.0) is-2.6 kcal/mol. The delta G0' (pH 7.0) for the hydrolysis of the phosphoryl bond in phosphocreatinine is-12.8 kcal/mol. The phosphocreatinine content of rabbit white skeletal muscle was measured to be 0.05 mumol/g, which is 0.4% of the phosphocreatine content. The in vitro experiments suggest that phosphohydrolysis of phosphocreatinine can account for a creatinine formation equal to 0.5% of the phosphocreatine content/day. We conclude that it is likely that a substantial fraction of the in vivo creatinine production from phosphocreatine goes through the novel high energy phosphate, phosphocreatinine, as an intermediate.


Subject(s)
Creatine/metabolism , Muscles/metabolism , Phosphocreatine/metabolism , Animals , Hydrogen-Ion Concentration , Kinetics , Magnetic Resonance Spectroscopy , Models, Biological , Phosphocreatine/isolation & purification , Rabbits , Spectrophotometry, Ultraviolet , Thermodynamics
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