On lactic dehydrogenase

Abstract

Preliminary observations. DURING an attempt to correlate the dehydrogenating activity of washed bacterial suspensions of B. coli with the number of living bacteria present, the rates of reduction of methylene blue by four hydrogen donators (glucose, succinate, formate and lactate) in the presence of the bacterial suspension were plotted at intervals against the viable count. It was soon found that, though the rates of reduction by the first three donators fell off continuously with the age of the suspension, that of the lactate first fell off, then became stationary and finally rose. This led to a search in the filtrate for a dehydrogenase which should activate lactate in preference to the other three substances. Strong evidence for the existence of this was forthcoming, but it was found that the dehydrogenase was better prepared by allowing thick bacterial suspensions to autolyse at 370; finally the following method of preparation was adopted.