The Nobel Prize in Chemistry 1970 was awarded to Luis Leloir "for his discovery of sugar nucleotides and their role in the biosynthesis of carbohydrates".
 

Carbohydrates form a comprehensive group of naturally occurring substances, which include innumerable sugars and sugar derivatives, as well as high-molecular carbohydrates (polysaccharides) like starch and cellulose in plants and glycogen in animals. In 1949 Leloir found that in a certain reaction, which results in the transformation of one sugar to another sugar, the participation of a so far unidentified substance was essential. He had found the key which would enable us to unravel an immense number of metabolic reactions. Leloir soon found that besides the sugar nucleotide first isolated, several others of the same type occur in Nature, and many have also been found by other research workers.