1910S-1930s, Gustav Embden and otto Meyerhof (Germany), studied muscle and its extracts Reconstructed all the transformation steps from glycogen to lactic acid in vitro revealed that many reactions of lactic acid (muscle)and alcohol (yeast) fermentations were the same Discovered that lactic acid is reconverted to carbohydrate in the presence of O2 (gluconeogenesis); observed that some phosphorylated compounds are energy-rich• 1910s-1930s, Gustav Embden and Otto Meyerhof (Germany), studied muscle and its extracts: – Reconstructed all the transformation steps from glycogen to lactic acid in vitro; revealed that many reactions of lactic acid (muscle) and alcohol (yeast) fermentations were the same! – Discovered that lactic acid is reconverted to carbohydrate in the presence of O2 (gluconeogenesis); observed that some phosphorylated compounds are energy-rich