Lyases are enzymes that catatyze the cleavage of C-C, C-O, C-N bonds by other means than by hydrolysis or oxidation. More specifically, these bonds are cleaved by the process of elimination and the resulting product is the formation of a double bond or a new ring. Lyases differ from other enzymes in that two substrates are involved in one reaction direction, but only one substrate is involved in the other direction. To generate either a double bond or a new ring, the enzyme is acted upon the single substrate and a molecule is eliminated. Lyases can be seen in the reactions of the Citric Acid Cycle (Krebs cycle) and in glycolysis.