Biochemistry.

While biochemistry encompasses the study of any cell process using either organic (carbon-carbon bonding) or inorganic substances, its eighteenth-century origins focused largely on the chemistry of plant and animal proteins. Scientists recognized that protein could be digested using stomach secretions and, later, observed that saliva would convert starch into simpler sugars. However, the mechanism behind these reactions remained a mystery. In the nineteenth century, French chemist Louis Pasteur hypothesized that the process of sugar converting to alcohol during fermentation must be catalyzed (sped up) by a substance synthesized in living cells. Some years later, the term “enzyme” was coined by German physiologist Wilhelm Kühne to explain the reaction. During the 1920s, James Sumner demonstrated the protein nature of most enzymes.