[Comparative study of properties of two extracellular protectors, isolated from Escherichia coli at elevated...

The regularities of the formation and action, as well as some physicochemical properties, of two extracellular protectants secreted by Escherichia coli cells under the condition of heat shock (a temperature increase from 37 to 46-49 degrees C), were investigated. Both factors, "antilysin" (factor X(I)), either protecting from, or diminishing, cell lysis under the action of 9 microM N-ethylmaleimide (NEM), and "mu-reducer" (factor X(II)), reducing the rate of culture growth after a 60-min incubation and increasing culture viability in the presence of 200 microM NEM, were shown to be low-molecular-weight substances (less than 10 kDa) stable at extreme (pH values pH 1 and pH 11). Factors X(I) and X(II) differed in the dynamics of their accumulation in the culture liquid under unfavorable conditions and in the dependence pattern of their action upon concentration. Unlike factor X(II), factor X(I) was highly unstable during heating and storage. By their characteristics, X(I) should be considered a protectant, or an adaptogen of direct action, and X(II) to an inductor activating the cellular system to enhance cell viability.