Figure 1. .

Comparison of activity, expression, and tissue localization of VLCAD, ACAD9, and LCAD. The specific activity of VLCAD, ACAD9, and LCAD, as measured with palmitoyl-CoA, was 13, 1.2, and 0.9 U/mg, respectively (a). All substrates used are described in the “Methods” section. b and c, Expression of mRNA of ACAD9 and LCAD (b) and VLCAD, MCAD, and SCAD (c), measured in 21 human tissues by real-time RT-PCR and compared with the relative level of expression in muscle. The ratio of expression of VLCAD, ACAD9, LCAD, MCAD, and SCAD in muscle to the housekeeping gene GUSB was 34, 1.0, 0.4, 4.9, and 17.1, respectively. d, Immunoinactivation of ACAD activity in human liver, muscle, and brain, measured with C18:0-CoA as substrate. VLCAD antibodies inactivated 32%, 100%, and 0% of the activity measured in the mitochondrial membrane fraction of human liver, muscle, and brain, respectively, whereas ACAD9 antibodies inactivated 41%, 0%, and 100% in these same tissues.