Reaction of silver ions and some amino acids

The antimicrobial effectiveness of silver ions is a well-known function as an oligodynamic effect. We examined the reactivity of various amino acids and silver ions to reseach the antimicrobial action of silver ions. We titrated each of 20 kinds of amino acid solution with silver nitrate solution, and measured the concentrations of silver ions in each of the solutions with a silver ion electrode. By this analysis, we investigated the degree of reaction between varieties of amino acids and silver ions. We could, consequently, compare the relative strength of reaction between the silver ions and various amino acids. Silver ions were found to be strongly reactive especially to cysteine. Silver ions were also found to be reactive to arginine, histidine, lysine, and methionine. In addition, as a result of the infrared spectrum analysis for the silver cysteine compound, it was found that hydrogen in the mercapto group of cysteine had a substitutive reaction against silver ions. In reports, bacteria had a high receptivity to silver ions. Considering that bacteria contain metabolic enzymes in the cell membrane, it is thus assumed that the silver ion comes into contact with the enzyme containing cysteine inside the cell membrane, and the antimicrobial effect is expressed through enzyme inhibition.