FERMENTATION AND GLYCOLYSIS

As early as 1912 Embden, encouraged by the knowledge of cell-free fermentation in yeast juice, became interested in the possibility of obtaining from muscle a soluble system capable of forming lactic acid from carbohydrate. He used an adaptation of the technique of Buchner (1). Dog muscle, obtained with cooling precautions from the animal under narcosis, was minced and frozen; it was ground with sand, mixed with kieselguhr to obtain a slightly damp mass, and squeezed in a Buchner press. When the resulting press-juice was incubated at 40° for 2 hours, lactic acid formation took place. No increase in formation was found on addition of glycogen, glucose, inositol or alanine. This was very surprising, in view of the wellknown production of lactic acid on perfusion of a glycogen-rich liver; or of a glycogen-poor liver, if the perfusing blood contained glucose. Embden suggested the name ‘lactacidogen’ for the unknown precursor.

Embden recalled that early work had often connected muscular exercise with increased formation of free phosphate. Thus G. J. Engelmann (1) in 1871 had first recorded increased phosphoric acid excretion in the urine after very strenuous work; this observation was confirmed by some later workers of the nineteenth century, but the effect could not be found by others. Mindful also no doubt of the already known importance of phosphate in fermentation in yeast press-juice, Embden and his collaborators proceeded to look for changes in inorganic phosphate concentration which might accompany lactic acid formation in muscle press-juice.