Saitoh T, Yoshida S, Takeshita M
Department of Biochemistry, Medical College of Oita, Japan.
Biochim Biophys Acta. 1988 Jun 15;960(3):410-6.
Characteristics of condensation and overall elongation of very-long-chain fatty-acyl-CoAs in swine cerebral microsomes were studied using radio high-performance liquid chromatography (RHPLC) and gas chromatography-mass spectrometry (GC-MS). The monounsaturated fatty-acyl-CoA depressed both the condensation and overall elongation activities of endogenous substrates and also of exogenous saturated fatty-acyl-CoA. The extent of the decrease of the elongation activity was dependent on the concentration and the chain length of the exogenous fatty-acyl-CoAs. The dependence of the condensation activity of monounsaturated fatty-acyl-CoA on the concentration of malonyl-CoA suggested that the non-Michaelis-Menten type kinetics was dominant for oleoyl-CoA, however, a normal kinetic pattern was obtained for endogenous palmitoyl-CoA and arachidonoyl-CoA with Km = 37 microM to malonyl-CoA. The condensation activity for icosanoyl-CoA (20:0-CoA) was inhibited by icosenoyl-CoA (20:1-CoA) in a non-competitive manner, which suggested that the condensation enzyme, or at least the active center of the enzyme for icosenoyl-CoA, was different from that for icosanoyl-CoA.
利用放射性高效液相色谱法（RHPLC）和气相色谱-质谱联用技术（GC-MS），研究了猪脑微粒体中极长链脂肪酰辅酶A的缩合及整体延伸特性。单不饱和脂肪酰辅酶A对内源底物以及外源饱和脂肪酰辅酶A的缩合和整体延伸活性均有抑制作用。延伸活性降低的程度取决于外源脂肪酰辅酶A的浓度和链长。单不饱和脂肪酰辅酶A的缩合活性对丙二酰辅酶A浓度的依赖性表明，油酰辅酶A的动力学类型为非米氏动力学，但内源性棕榈酰辅酶A和花生四烯酰辅酶A对丙二酰辅酶A的动力学模式正常，其米氏常数Km = 37 μM。二十碳烯酰辅酶A（20:1-CoA）以非竞争性方式抑制二十碳酰辅酶A（20:0-CoA）的缩合活性，这表明缩合酶，或者至少是二十碳烯酰辅酶A的酶活性中心，与二十碳酰辅酶A的不同。
