Background and purpose: Due to the beneficial physiological effects of conjugated linoleic acid (CLA), there has been a growing tendency to produce it as a functional lipid in recent years. Different CLA isomers have different physiological effects; hence, production of certain CLA isomers with high purity is of great importance. CLA can be produced through both chemical and enzymatic methods; however, unlike chemical catalysts, enzymes make it possible to produce pure CLA isomers. In this study, linoleic acid isomerase from Propionibacterium acnes was expressed in E. coli and the possibility of the production of CLA was studied.Materials and methods: The vector containing linoleic acid isomerase, pGEX-6P-PAI, was transformed inE. coli. Transformants were selected based on their resistance to ampicillin and restriction digestion analysis. To express the recombinant linoleic acid isomerase, transformants were induced using isopropyl-beta-thiogalactopyranoside (IPTG). The expression of recombinant protein was confirmed by SDS-polyacrylamide gel electrophoresis and Western blotting using anti-linoleic acid isomerase antibody. Then, the possibility of the production of CLA from Linoleic acid by usingE-coli transformant was investigated.Results: Recombinant linoleic acid isomerase was intracellularly produced as a glutathione Stransferase (GST) tagged protein by transformedE-coli. The fusion of GST to the N-terminus of linoleic acid isomerase increased its molecular weight from 49 to 75 kDa. GST-tagged enzyme acted like linoleic acid isomerase and the transformed bacterium could convert considerable amounts of linoleic acid to CLA.Conclusion: The findings indicated that transformed E. coli can be used for CLA production in biocatalytic processes.

Background: Most animal studies have shown that trans-10 and cis-12 isomers of Conjugated linoleic Acid, (CLA) tend to increase insulin resistance. But the effect of equal isomers of CLA (50: 50 ratios of cis-9, trans-11: trans-10, cis-12 isomers) on lipid profiles, glucose, and insulin resistance and sensitivity in postmenopausal women is not clear.Methods: In the present study, we performed a randomized, double blind, placebo-controlled trial to examine the changes in lipid profiles, glucose, and insulin concentration following 4 CLAG80 capsules containing 3.2g CLA (50: 50 ratios of cis-9, trans-11: trans-10, cis-12 isomers) or 4 placebo capsules supplementation for 12 weeks in post-menopausal women. Seventy six healthy post-menopausal women were randomized to receive placebo or 3.2 g CLA for 12 weeks. Anthropometric measurements were done. Blood samples were collected after 12-14 hours fasting before and after intervention. Insulin resistance and insulin sensitivity were estimated based on the homeostasis (HOMA) and QUIKI models. In weeks 0, 6 and 12 during the trial, subjects completed 3d dietary records. These dietary records were coded by the same dietitian, and analyzed with the Food Processor program. Result: There were no significant effect on serum lipids, insulin, glucose, insulin resistance and insulin sensitivity over 12 weeks in postmenopausal women.Conclusion: Mixed isomer CLA supplementation had no effect on serum insulin, lipids profile, glucose and insulin resistance/sensitivity during 12 weeks of intervention in postmenopausal women.

Although, most of the experimental studies demonstrated that conjugated linoleic acid has effects on metabolic syndrome, but the number of human studies in this area are limited and the result of these studies are controversial. This systematic review was conducted to summarize the literature from clinical trials and experimental studies regarding the effect of each conjugated linoleic acid (CLA) isomers on component of metabolic syndrome. Relevant studies were identified by searching scientific databases of PubMed and ISI during 2000 until 2012. Clinical trials and experimental studies regarding the effect of 9 cis, 11 trans and 10 trans, 12 cis and mixed CLA on component of metabolic syndrome including insulin resistance, obesity, dyslipidemia and hypertension were included in this systematic review. From 320 articles that were found in this area, 24 articles that had the inclusion criteria were selected. Most of the experimental studies have shown that conjugated linoleic acid can improve insulin resistance and lipid profile in animals, whereas clinical trials could not demonstrate this effects of CLA on humans. Each isomers of CLA have different effects, that is, 9 cis, 11 trans have role in reducing insulin resistance and improving lipid profile and 10 trans, 12 cis isomers have role in improving hypertension.