Abstract: | The transport of 2-methyl-4-amino-5-hydroxymethylpyrimidine (MAHMP) by Salmonella typhimurium was studied using synthetic [methyl-3H3]MAHMP. It was found that an active transport system existed for MAHMP, having Km of 0.07 μM and Vmax 45 nmol·min?1·(g dry wt. cells)?1, that required glucose as a source of energy and was pH and temperature dependent. Uptake was inhibited by cyanide, azide, N-ethylmaleimide, 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone. Uptake was also weakly inhibited by oxythiamine, but not by thiamine, 2-methyl-4-amino-5-aminomethylpyrimidine, or 4-amino-5-hydroxymethylpyrimidine, indicating that the transport system is specific for MAHMP. |