Argentine chemist who studied glucose metabolism and discovered an alternative mechanism for glycogen synthesis, involving a new enzyme. Later, he connected these reactions to glycogen synthesis in the liver and muscles. He showed that a glucose molecule is added by a process in which the reactive intermediate uridine diphosphateglucose (UDPG) transfers glucose to the growing glycogen chain. He found that galactose is broken down to yield glucose in a similar pathway. He was awarded the Nobel Prize for Chemistry in 1970 for his discovery of sugar nucleotides and their role in carbohydrate biosynthesis.
Gerty Cori had previously demonstrated a pathway in which glycogen (a polysaccharide made from glucose) is both synthesized and converted to other products. But Leloir identified the enzyme glucose-phosphate kinase acting in a separate glycogen synthesis. The product of this reaction, glucose 1,6-bisphosphate, is a coenzyme of the glycolysis pathway enzyme, phosphoglucomutase. He went on to identify galactokinase and discovered that the product, galactose 1-phosphate, is converted into glucose 1-phosphate.
Leloir was born in Paris, France, to Argentine parents. He studied at Buenos Aires University, where he graduated in medicine in 1932, and spent a year at Cambridge, England under the guidance of Frederick Gowland Hopkins. He briefly returned to Argentina to work at the Institute of Physiology; however, his ideas clashed with those of President Juan Perón, and Leloir went into exile in the USA. But soon afterwards he returned to Argentina and founded his own research institute, the Biochemical Research Institute, in 1945.