2-chloroethanol mutagenicity

The mutagenicity of chloroethylene oxide, chloroacetaldehyde, 2-chloroethanol and chloroacetic acid, conceivable metabolites of vinyl chloride

Previous investigations have shown that the carcinogen vinyl chloride causes base-pair substitution in the bacterium. The ability of four conceivable metabolites — chloroethylene oxide, chloroacetaldehyde, 2-chloroethanol and chloroacetic acid — to cause base-pair substitution directly inTA1535 has been compared. The main comparison was performed at initial concentrations from 0.1 to 1.5 mM. In this region, however, a mutagenic effect was observed only with chloroethylene oxide and chloroacetaldehyde, the former being approximately 20 times more effective than the aldehyde when compared on a molar basis. 2-Chloroethanol and chloroacetic acid were studied also at higher concentration (1 mM-1 M), and a weak mutagenic response was found with 1 M 2-chloroethanol solution. With chloroacetic acid no enhancement of the mutation frequency could be detected.Chloroethylene oxide was found to be approximately 450 times more effective as a mutagen than chloroacetaldehyde when the comparison is based on exposure doses, defined as the time-dependent concentrations of the compounds in the treatment solutions, integrated between the times of onset and termination of treatment. Similarly, chloroethylene oxide was 10 000–15 000 times more effective as a mutagen than ethylene oxide, used as a positive control.

The Configuration of Ribonuclease at Low pH in 2-Chloroethanol and in 2-Chloroethanol-Water Mixtures1

Imahori, Klemperer and Doty have shown that ribonuclease dissolved in 2-chloroethanol acquires a configuration characterized by a high content of helical polypeptide structure. This paper shows that the transition from native aqueous ribonuclease to the highly helical structure occurs in two stages, through an intermediate with about the same helix content as aqueous ribonuclease but with a high intrinsic viscosity and flexibility, which suggests that its non-helical portions are more or less randomly coiled. The highly helical structure in chloroethanol is presumably the result of intramolecular hydrogen bonding; the compact configuration in aqueous solution is ascribed primarily to hydrophobic forces.