very different. The Kcat/Km ratio in cotyledons is 10^6 M-1s-1 which outperforms the ratio .07 * 10^6 M-1s-1. Due to a high turnover rate, the plant peroxisomes contain a lesser amount of enoyl-CoA isomerase than their counterparts in the rat liver. In rat liver, mitochondrial enoyl CoA isomerase and peroxisomal enoyl CoA isomerase embedded in the multifunctional enzyme have similarities in the primary structure sequence. When comparing the amino-terminal half of E. coli against the amino-terminal half of rat liver, there were primary and secondary structure similarities towards the middle of the amino-terminal end. This conserved region must be important for structure and function of this specific enzyme since showing equally in both E. coli and rat liver. Structure All classes of enoyl-CoA isomerases belong to a family of enzymes, the hydratase/isomerase or crotonase superfamily, and when examined with x-ray crystallography, exhibit a common structural feature of the family, the N-terminal core with a spiral fold composed of four turns, each turn consisting of two beta-sheets and one alpha-helix. In enoyl-CoA isomerase, the two beta-sheets are part of the catalytic site, since the NH groups of residues following the beta-sheets attach to the carbonyl oxygen of the acyl-CoA intermediate. The formation of this oxyanion hole stabilizes the transition state of the enzyme-catalyzed reaction. Moreover, a glutamate residue located next to body cavities filled with water molecules and lined with hydrophobic or apolar side chains has also been identified as a part of the catalytic site. In its deprotonated form, the glutamate can act as a base and remove a proton from the acyl-CoA intermediate. The body cavities aid in rearranging the glutamate side chain to retain the proton and later deliver it back to the acyl-CoA, on a different carbon position. The NH-containing residues have been identified as Ala70 and Leu126 and the glutamate as Glu158 in peroxisomal enzymes in a yeast species, Saccharomyces cerevisiae. Their relative locations on the enzyme can be compared in figure 2. The enzymes of the hydratase/isomerase or crotonase superfamily are typically trimeric disks dimerized into hexamers. The wide range of their substrate-enzyme specificity derives from the variations in the distances between the trimeric disks and their orientation. However, the human mitochondrial enoyl-CoA isomerase is a trimer and orients the fatty acid tail in a completely different direction from that seen in the hexamers. The trimeric disk of peroxisomal enzymes in Saccharomyces cerevisiae is displayed