in figure 3. History Enoyl-CoA isomerase was first identified and purified from rat liver mitochondria in the 1960s and 1970s via gel filtration and ion exchange chromatography. Since then, all classes of enoyl-CoA isomerase, mitochondrial, peroxisomal and multifunctional, have been identified in different organisms, including more mammals, plants, and unicellular organisms. By 1994, using the rat enoyl-CoA isomerase cDNA as a hybridization probe, human enoyl-CoA isomerase cDNA could be sequenced and cloned. In the same year, the protein itself was isolated, not by affinity to rat antibody or cDNA probes, but by copurification with a transferase, human glutathione S-transferases. In the attempts to examine the human enoyl-CoA isomerase in detail, the mitochondrial enzyme in the mammalian liver was identified as a potential biological marker for metabolic diseases due to its elevated levels in defective cells, and linked defects in fatty acid beta-oxidation to human diseases, to be specified in the next section. Clinical significance In humans, defects in the beta-oxidation mechanism result in hypoketotic hyperglycemia, a symptom of starvation, due to the inefficient utilization of fatty acids as a primary source of energy. The metabolic disease was found to be on a genetic level: rats without the genes for enoyl-CoA isomerase also displayed high blood glucose level. Moreover, a biological marker for this condition may have been identified as the urine of these rats included high concentrations of medium chain unsaturated dicarboxylic acids, a condition called dicarboxylic aciduria. More recent studies link hepatitis C virus (HCV) infection to defects in fatty acid degradation, specifically, to that in enoyl-CoA isomerase. HCV is the leading cause of chronic hepatitis, cirrhosis, and liver cancer, and more than 180 million people are affected globally. Due to the prolonged latency of the virus and no existing cures to rid the virus specifically, HCV is a serious problem that is causing more deaths than HIV/AIDS in the United States, but its threat still do not receive adequate attention. The need for a HCV-specific treatment is essential, and according to John Ward, the director of the CDC Hepatitis Division, it can save up to 120,000 lives. According to protein profiling in the human liver biopsies of HCV patients, a correlation was initially discovered between dysfunctional mitochondrial processes, which include beta-oxidation, and HCV. As a matter of fact, lipids play an important role in the replication cycle of HCV, and in the "in vivo" samples from HCV patients,