Substrate preference and enzyme kinetics for long chain acyl-CoA synthetase isoform 1 (2010)
Undergraduate: Shannon Mentock
Faculty Advisor: Rosalind Coleman
Department: Nutrition
Long chain acyl-CoA synthetases (ACSL) esterify long chain fatty acids to form long chain acyl-CoAs. Fatty acid preference of ACSL determines the composition of end products from long chain acyl-CoAs, such as membrane phospholipids. Fatty acid preferences for purified rat ACSL1-6 were characterized by the Yamamoto group in Japan, and ACSL isoform 1 did not have a significant fatty acid preference.
High preference in heart total particulate for linoleic acid compared to palmitic acid led to further investigation of in vivo ACS preference and to a reevaluation of purified ACSL1 preference. Substrate dependence curves were completed using an isotope assay for palmitic and linoleic acids (5-100 µM) in control and ACSL1 total body knockout heart total particulate and for palmitic, stearic, oleic, and linoleic acids (20-200 µM) in purified ACSL1.
Purified ACSL1 and heart total particulate had dramatic preference for linoleic acid that was 7 and 8.6 times that for palmitic acid, respectively. Preferences for stearic and oleic acids were 1.2 and 2.1 times that for palmitic acid in purified ACSL1, respectively, whereas stearic and oleic acids were 0.7 and 0.3 times that for palmitic acid in heart total particulate, respectively. This data suggests that ACSL1 has significant fatty acid species preference, and thus, previous preferences for ACSL1 may need to be reevaluated.