Toxic fluorine compounds

Prolegomena to Future Experimental Efforts on Genetic Code Engineering by Expanding Its Amino Acid Repertoire

Protein synthesis and its relation to the genetic code was for a long time a central issue in biology. Rapid experimental progress throughout the past decade, crowned with the recently elucidated ribosomal structures, provided an almost complete description of this process. In addition important experiments provided solid evidence that the natural protein translation machinery can be reprogrammed to encode genetically a vast number of non-coded (i.e. noncanonical) amino acids. Indeed, in the set of 20 canonical amino acids as prescribed by the universal genetic code, many desirable functionalities, such as halogeno, keto, cyano, azido, nitroso, nitro, and silyl groups, as well as C=C or C[triple bond]C bonds, are absent. The ability to encode genetically such chemical diversity will enable us to reprogram living cells, such as bacteria, to express tailor-made proteins exhibiting functional diversity. Accordingly, genetic code engineering has developed into an exciting emerging research field at the interface of biology, chemistry, and physics.

The biochemical pathway for the breakdown of methyl cyanide (acetonitrile) in bacteria

[2-14C]Methyl cyanide (acetonitrile) is metabolized to citrate, succinate, fumarate, malate, glutamate, pyrrolidonecarboxylic acid and aspartate. Non-radioactive acetamide and acetate compete with 14C from methyl cyanide, and [2-14C]acetate and [2-14C]methyl cyanide are metabolized at similar rates, giving identical products. This evidence, combined with the inhibitory effect of fluoroacetate and arsenite on methyl cyanide metabolism, indicates that the pathway is: methyl cyanide leads to acetamide leads to acetate leads to tricarboxylic acid-cycle intermediates. The pathway was investigated in a species of Pseudomonas (group III; N.C.I.B. 10477), but comparison of labelling patterns suggests that it also exists in several higher plants.

A TOXICOLOGICAL AND BIOCHEMICAL STUDY OF ω-FLUORO COMPOUNDS

A series of ω-fluoro compounds have been examined for their toxicity to mice and their ability to cause accumulation of citric acid in vivo. It was found that the toxic members did cause citric acid accumulation. Since fluoroacetate causes citric acid accumulation, it was concluded that the activity of these compounds and their effect on citric acid levels is in agreement with the hypothesis that these compounds were degraded to a fluoroacetyl derivative. The findings suggested that mice can degrade to fluoroacetate, compounds containing the following terminal radicals: amine, nitro, nitrile, thiocyanate, isothiocyanate, mercaptan, fluoride, chloride, bromide, iodide, tosylate, mesylate, 2-ketone, sulphonyl chloride, 1-alkyne, ether, substituted urea, aldehyde, and carboxyl. When compared on a molar basis several of the toxic compounds containing four or more carbon atoms were more toxic than fluoroacetate. 6-Fluorohexylamiue and 6-fluorohexanoic acid, which were representative of this type of compound, were investigated in this regard. These compounds, like fluoroacetate, were not immediately reactive but appeared to be converted to the toxic end-product more efficiently. In the dog, death from 6-fluorohexylamine was due to respiratory failure.