The American Heritage® Dictionary of the English Language, 4th Edition
n. Any of a group of enzymes that catalyze the formation of double bonds by removing chemical groups from a substrate without hydrolysis or catalyze the addition of chemical groups to double bonds.
n. Any of many classes of enzyme that catalyze the breaking of a specific form of bond
Word Usage
"Garcinia Cambogia: is a natural form of Hydroxcitric acid (HCA) which can inhibit an enzyme in cells, citrate lyase, which is needed for the conversion of carbohydrates into fat."