266 1. lODOACETATE AND lODOACETAMIDE 



uptake of labeled phosphate into the DNA of radiosensitive tissues and 

 regenerating liver, so that the effects of radiation and iodoacetate are ad- 

 ditive. It is often difficult to interpret the results of such work as presented 

 in this section, inasmuch as ordinary and expected summation of effects 

 is not distinguished from true potentiation. 



EFFECTS ON THE GROWTH OF MICROORGANISMS 



The value of simple bacteriostatic studies with iodoacetate is only that 

 bacteria differ so much in inherent metabolic patterns that it is interesting 

 to compare their relative sensitivities on this basis. In addition, there is the 

 possibility of using iodoacetate or derivatives as antiseptics. One must be 

 particularly careful in attributing growth inhibition in microorganisms to 

 a block of the EM pathway, because there may be other susceptible path- 

 ways, and furthermore actions on the cell surface or transport systems are 

 quite possible. Bacteria are also very often grown in complex culture media 

 providing substrates which may be utilized to circumvent a block of the 

 EM pathway. 



Bacteria 



Some idea of the general susceptibility of bacteria to iodoacetate may 

 be obtained by giving a few selected results expressing inhibitory concen- 

 trations: Staphylococcus aureus is inhibited 50% by 0.063 mM (Yanagita, 

 1947), various homofermentative lactobacilli are minimally inhibited by 1 

 mM and heterofermentative lactobacilli by 2.5 mM (Fitzgerald and Jordan, 

 1953), Enterococcus is inhibited minimally by 0.05 mM and markedly by 

 0.1 raM (Meyer, 1932), Proteus vulgaris is inhibited somewhat by 2 mM 

 (Kandler et al., 1956), Escherichia coli is inhibited 50% by 0.11 mM (Love- 

 less et al., 1954), Thiobacillus thiooxidans is completely inhibited by 0.01 

 mM (Vogler et al., 1942), and Mycoplasma gallisepticum is not inhibited 

 by 0.1 mM, although the stimulation of growth by glucose is inhibited 

 (Gill, 1962). It is interesting that the high sensitivity of T. thiooxidans is 

 associated with a very marked inhibition of sulfur oxidation by iodoacetate. 

 Various derivatives of bromoacetate, for example the benzyl ester, have 

 been used as antiseptics commercially, as in wine making, under the trade 

 names of Antiferm and Fermacid (Eeckhout, 1948; Loncin, 1950; Dal-Cin, 

 1950). Germination of Bacillus coagulans spores induced by alanine is re- 

 sistant to 5 mM iodoacetate, but germination brought about by glucose 

 in heated spores is 98% inhibited, so that the activation in the latter case 

 must be through glycolysis (Amaha and Nakahara, 1959). Flagellar motility 

 in Bacillus brevis is inhibited rapidly by iodoacetate and iodoacetamide, 

 but high concentrations (10 mM) were used (De Robertis and Peluffo, 

 1951). 



