Glucuronic Acid: A Study of Its Chemistry and Role in Animal Metabolism

Paul, John (1952) Glucuronic Acid: A Study of Its Chemistry and Role in Animal Metabolism. PhD thesis, University of Glasgow.

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1) An observation on the behaviour of glucurone in strong alkali is reported, and its significance discussed. 2) An attempt to prepare glucuronic acid from the hydrolysis of starch oxidised with nitrogen dioxide is reported. 3) The naphthoresorcinol reaction for the estimation of glucuronic acid has been reinvestigated. a) The tolerance has been markedly extended by the addition of an oxidising agent to the reaction mixture. b) The use of sulphuric acid has been found superior to hydrochloric acid and permits the use of higher concentrations of naphthoresorcinol. c) Owing to the achievement of more reliable blank readings by these modifications, accuracy has been increased. d) Owing to the use of a higher naphthoresorcinol concentration than commonly employed, sensitivity has been increased. e) By the use of more critical solvents than usually employed, specificity has been made almost absolute in relation to the true sugars, and has been greatly increased otherwise. f) By a systematic investigation of the mechanism of the reaction and of the effect of interfering substances, methods have been devised to circumvent their influence. 4) A technique employing ion-exchange resins has been developed for the concentration of glucuronides from very dilute solutions. It is not yet directly applicable to urine. 5) Methods of partition chromatography have been developed for the separation and identification of glucuronides, employing both filter-paper and column chromatograms. Natural Occurrence and Synthesis of Glucuronides. Section 3. 1) The naphthoresorcinol reaction, as modified in the present work, has been found to be directly applicable to human urine but not to rabbit urine, in a series of pilot experiments. 2) By neutralising the reducing effect of the glucose in blood by means of an oxidising agent, it has been found possible to estimate directly the glucuronic acid in deprotein-ised blood by means of the naphthoresorcinol reaction. 3) After the removal of mucin, evidence has been obtained for the presence of glucuronic acid in bile. 4) A preliminary series of experiments on the in vitro synthesis of glucuronides in liver slices is reported. a) The process was inhibited by cyanide, fluoride and iodoacetate. b) Synthesis in breis could be achieved by the use of boiled liver extracts but not by the addition of saccharate, cytochrome C, adenosine triphosphate or combinations of these. c) It was not increased by the addition of glucose, glucuronic acid, or pyruvic acid to the medium, except on an occasion when magnesium was omitted, activity then being increased by all three. d) Synthesis was greatly increased by the use of a bicarbonate saline in place of a phosphate medium. e) Synthesis was only found to occur to a significant degree in liver slices, to a smaller degree in kidney, and to a very small and dubious degree in intestinal mucosa. f) Inhibition by iodoacetate was reversed by the addition of glucurone to the medium. This observation is considered highly important and is discussed. 5) No significant difference in synthetic ability was found betweem the livers of normal rats and the livers of rats after hepatectomy, rats with fatty livers and pregnant rats. Biological Degradation of Glucuronides. Section 4. 1) The results of investigations into the physical properties of glucuronidase are reported. a) Evidence for the existence of at least three, and probably four different enzymes with glucuronidase activity has been obtained. b) These enzymes have different pH optima, substrate-enzyme dissociation constants and activation energies and their behaviour towards inhibitors differs widely. Reasons for this behaviour are discussed. c) Attempts have been made to separate these by the application of a number of techniques, some of which are novel. Only partial success has been attained to date. (Abstract shortened by ProQuest.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Biochemistry, Physiology
Date of Award: 1952
Depositing User: Enlighten Team
Unique ID: glathesis:1952-78832
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 14:49
Last Modified: 30 Jan 2020 14:49

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