Answer
Cori ester, an essential compound identified by the Coris, played a crucial role in their biochemical studies. This compound, named after its discoverers, was a key intermediate in the metabolism of carbohydrates and was instrumental in understanding the processes of glycolysis and glycogenolysis. The Coris' identification of Cori ester significantly contributed to the advancement of biochemistry and provided insights into the regulation of energy metabolism in living organisms.