Fatty acid synthetase complex from the insect Ceratitis capitata.
Fatty acid synthesis capacity of the insect Ceratitis capitata has been investigated in vitro from [1-14C]acetyl-CoA using homogenates at different stages of development. A maximum activity was observed after 5--6 days of larval development. But homogenates of the pharate adult insect did not show synthetic capacity of fatty acids. Fatty acid synthetase complex has been isolated from the particle-free supernatant fraction of homogenates from the 6-day C. capitata larvae. The enzyme complex was purified 182-fold with respect to the protein contained in the crude extract. The complex was homogeneous when analysed by gel filtration and by polyacrylamide-gel electrophoresis. The molecular weight was 5.2X10(5). The enzyme was dissociated into half-molecular subunits. Amino acid analysis, general properties, stability and kinetic constants (V and Km) for the substrates are reported. The fatty acid synthetase complex from the insect contains 42+/-1-SH residues and one phosphopatetheine moiety per 5.2X10(5). Activity was dependent on the presence of NADPH; FMN strongly inhibited the enzyme activity promoted by NADPH. The enzyme complex synthesized a range of fatty acid (10:0--18:0), palmitate being the predominant end product. The proportions of fatty acids synthesized varied with substrate concentrations. Fatty acids released from the complex were almost completely in the free form.
Fatty acid synthetase complex from the insect Ceratitis capitata. Fatty acid synthesis capacity of the insect Ceratitis capitata has been investigated in vitro from [1-14C]acetyl-CoA using homogenates at different stages of development. A maximum activity was observed after 5--6 days of larval development. But homogenates of the pharate adult insect did not show synthetic capacity of fatty acids. Fatty acid synthetase complex has been isolated from the particle-free supernatant fraction of homogenates from the 6-day C. capitata larvae. The enzyme complex was purified 182-fold with respect to the protein contained in the crude extract. The complex was homogeneous when analysed by gel filtration and by polyacrylamide-gel electrophoresis. The molecular weight was 5.2X10(5). The enzyme was dissociated into half-molecular subunits. Amino acid analysis, general properties, stability and kinetic constants (V and Km) for the substrates are reported. The fatty acid synthetase complex from the insect contains 42+/-1-SH residues and one phosphopatetheine moiety per 5.2X10(5). Activity was dependent on the presence of NADPH; FMN strongly inhibited the enzyme activity promoted by NADPH. The enzyme complex synthesized a range of fatty acid (10:0--18:0), palmitate being the predominant end product. The proportions of fatty acids synthesized varied with substrate concentrations. Fatty acids released from the complex were almost completely in the free form.