Definition of Enzymes

Enzymes: Proteins that act as a catalysts in mediating and speeding a specific chemical reaction.

In 1902 Archibald Garrod first attributed a disease to an enzyme defect: an inborn error of metabolism. Today, newborns are routinely screened for certain enzyme defects such as PKU (phenylketonuria) and galactosemia, an error in the handling (metabolism) of the sugar galactose.