Abstract
It was reported that thiamine kinase in the membrane fraction participated in the transport of thiamine by Escherichia coli. This fact led me to study on riboflavin uptake and localizations of riboflavin kinase and FAD pyrophosphorylase in E. coli. Riboflavin uptake by growing and resting cells of E. coli K_<12> was not observed by fluorometrical measurement as already reported by Wilson and Pardee. Riboflavin kinase and FAD pyrophosphorylase were easily extracted from the sonicated cells and was not localized in the membrane fraction differing from thiamine kinase of E. coli. No changes of the both enzyme activities by riboflavin addition to the growth medium were also observed.
