The introduction surveys the role of organic fluorine compounds in biology, and it is shown that the disruption of cellular metabolism by these compounds may be due not only to their action as specific enzyme inhibitors but also to their ability to become incorporated into the macromolecules of the cell. The usefulness of covalently-bonded fluorine in the design of analogues is shown to be related to its size, electronegativity, and the stability of the carbon-fluorine bond. The physical similarities between covalently-bonded fluorine and the hydroxyl group are argued to provide a rationale for the synthesis and biochemical investigation of deoxyfluoro sugars. A review of the effects and uses of such compounds in biology is included. The object of the present investigation has been to examine some of the biological effects of 3-deoxy-3-fluoro-D-glucose (3FG), and for this purpose three saprophytic soil bacteria were chosen. Results may be summarised thus 1. Neither whole cells nor cell-free extracts of E.coli metabolise 3-deoxy-3-fluoro-D-glucose. Simultaneous glucose oxidation by whole cells is not inhibited by the fluoro analogue, but an elevated extent of glucose oxidation subsequent to treatment with 3-deoxy-3-fluoro-D-glucose is found. Possible explanations for this are discussed. Preincubation with 3-deoxy-3-fluoro-D-glucose inhibits the subsequent growth of E.coli on glucose. 2(a). The effect of 3-deoxy-3-fluoro-D-glucose on glucose-grown Ps.fluorescens at two different buffer concentrations has been examined.;In 0.067M buffer staring concentrations of analogue varying from 5-30 mM are oxidised with the consumption of one oxygen atom per mole of substrate and concomitant acid production. At this buffer molarity with substrate concentrations in excess of 30 mM the acidic oxidation product sufficiently lowers the buffer pH as to completely inhibit further cellular oxidations and to cause cell lysis and death. In 0.67M buffer all concentrations of 3-deoxy-3-fluoro-D-glucose examined are oxidised with the consumption of one oxygen atom per mole of substrate, and without any inhibition of subsequent cellular oxidations. An explanation is proposed for the increased release of E260- absorbing material during oxidation of the analogue at this buffer molarity, which occurs without a corresponding drop in cell viability. (b) Cell-free extracts of Ps.fluorescens oxidise 3-deoxy-3-fluoro-D-glucose with the consumption of one mole of oxygen per mole of substrate and the reduction of cytochrome pigments. Explanations for the limitation of whole ceil oxidation of 3-deoj-3-fluoro-D-glucose in the light of the extent of oxidation by cell-free extracts are discussed (c) Chromatographic and manometric evidence favours 3-deoxy-3-fluoro-D-gluconic acid (3FGA) as the product of 3-deoxy-3-fluoro-D-glucose oxidation. (d) Whole cells and extracts of glucose-grown Ps.fluorescena oxidise 3-deoxy-3-fluoro-D-gluconate with the consumption of one atom of oxygen per mole of substrate, and the formation of a reducing compound tentatively considered to be 3-deoxy-3-fluoro-2-keto-D-gluconic acid (3F2KGA). (e) Though 3-deoxy-3-fluoro-D-gluconate is not oxidised by asparagine-grown cell suspensions of Ps.fluorescens, it inhibits the formation of the gluconate-oxidising system in these cells.;(f) 3-Deoxy-3-fluoro-D-glucose does not itself support the growth of Ps.fiuorescens and inhibits the growth of this organism on glucose. 3. Whole cell suspensions of Ps.saccharophila do not oxidise 3-deoxy-3-fluoro-D-glucose nor is glucose metabolism outwardly affected by the analogue. The differing oxidative abilities of the three organisms towards 3-deoxy-3-fluoro-D-glucose, outlined above, is discussed with reference to their differing enzymic complements. The appendices review synthetic routes to deoxyfluoro sugars and detail the synthesis of 3-deoxy-3-fluoro-D-gluconic acid.
|Date of Award||1970|