Hendrickson H S, Giles A N, Vos S E
Department of Chemistry, University of Washington, Seattle 98195, USA.
Chem Phys Lipids. 1997 Sep 24;89(1):45-53. doi: 10.1016/s0009-3084(97)00059-5.
Phosphatidylinositol-specific phospholipase C (PI-PLC) was studied with sonicated dispersions of a thiophosphate analog of phosphatidylinositol, 1, 2-dimyristoyloxypropane-3-thiophospho(1D-1-myo-inositol) (D-thio-DMPI). Kinetic parameters were derived from the rate as a function of bulk lipid concentration at constant saturating surface concentration of substrate (case I), and as a function of surface concentration of substrate at a constant saturating bulk concentration of lipid (case II). The substrate, D-thio-DMPI, was diluted with L-thio-DMPI or dimyristoyl phosphatidylmethanol (DMPM). In the presence of L-thio-DMPI, values for Vmax = 133 mumol min-1 mg-1, Ks' (the apparent dissociation constant for the enzyme-interface complex) = 0.097 mM, and Km* (the apparent interfacial Michaelis constant) = 0.22 mol fraction were obtained. DMPM caused enzyme inhibition in case I but no inhibition in case II. L-Thio-DMPI is an ideal neutral diluent with which to study the kinetics of PI-PLC.
利用磷脂酰肌醇的硫代磷酸类似物1,2 - 二肉豆蔻酰氧基丙烷 - 3 - 硫代磷酸（1D - 1 - 肌醇）（D - 硫代 - DMPI）的超声分散液对磷脂酰肌醇特异性磷脂酶C（PI - PLC）进行了研究。动力学参数是根据在底物饱和表面浓度恒定的情况下反应速率与脂质体浓度的函数关系（情况I），以及在脂质饱和体相浓度恒定的情况下反应速率与底物表面浓度的函数关系（情况II）得出的。底物D - 硫代 - DMPI用L - 硫代 - DMPI或二肉豆蔻酰磷脂酰甲醇（DMPM）进行稀释。在L - 硫代 - DMPI存在的情况下，得到的Vmax值为133 μmol min⁻¹ mg⁻¹，Ks'（酶 - 界面复合物的表观解离常数）为0.097 mM，Km*（表观界面米氏常数）为0.22摩尔分数。在情况I中，DMPM会导致酶抑制，但在情况II中不会。L - 硫代 - DMPI是研究PI - PLC动力学的理想中性稀释剂。
