Yamaguchi Takashi, Murano Takeyoshi, Tatsuno Ichiro, Hiruta Nobuyuki, Suzuki Toru, Sawada Shojiro, Katagiri Hideki, Shirai Kohji, Schneider Wolfgang J, Bujo Hideaki
1 Center of Diabetes, Endocrinology and Metabolism, Toho University Sakura Medical Center, Sakura, Japan.
2 Department of Clinical-Laboratory and Experimental-Research Medicine, Toho University Sakura Medical Center, Sakura, Japan.
Ann Clin Biochem. 2017 Nov;54(6):712-715. doi: 10.1177/0004563217693258. Epub 2017 Jan 23.
Background We investigated the in vitro effects of various phospholipids as emulsifiers on the hydrolysing activities of lipoprotein lipase (LPL) Arg243His against triolein as substrate. LPL Arg243His, identified in a patient with hyperchylomicronaemia, displays severely diminished activity for triolein when emulsified with Triton X-100. Methods Lipolytic activities of plasma obtained by heparin injection from a homozygous patient with LPL Arg243His were analysed using triolein emulsified with phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), lysophosphatidylcholine (LPC), or Triton X-100 as substrates. Results The hydrolysing activities of the patient's plasma for triolein emulsified with PC, PE, PS, PI, LPC and Triton X-100 were 9.22 ± 1.06 μmol/ml/h/ngLPL, 2.94 ± 1.60 μmol/ml/h/ng LPL, 3.72 ± 1.63 μmol/ml/h/ng LPL, 3.40 ± 1.20 μmol/ml/h/ngLPL, 3.72 ± 1.96 μmol/ml/h/ngLPL and 7.80 ± 4.48 μmol/ml/h/ng LPL, respectively. Thus, the specific activities of the patient's LPL determined with triolein emulsified with PC were significantly higher than those with PE, PS, PI or LPC as emulsifiers. Relative to the activities of normal plasma measured with PC, PE, PS, PI and LPC as emulsifiers, the mutant's activities were 49.1 ± 5.2%, 44.1 ± 5.7%, 31.7 ± 12.6%, 19.2 ± 6.9% and 23.8 ± 11.3%, respectively. Using PC, PE, PS, PI and LPC as emulsifiers, the mutant's activities for triolein-lipolysis relative to normal were significantly increased in comparison to the relative activity measured with the classical emulsifier, Triton X-100 (12.9 ± 6.7%). Conclusions Impaired triolein hydrolysis by LPL Arg243His was partially ameliorated by triolein emulsification with phospholipids. The in vitro analysis of triolein hydrolysis using various phospholipid emulsifiers may be useful for the further understanding of impaired LPL function.
我们研究了各种磷脂作为乳化剂对脂蛋白脂肪酶（LPL）Arg243His水解以三油酸甘油酯为底物的体外作用。在一名高乳糜微粒血症患者中鉴定出的LPL Arg243His，在用 Triton X-100乳化时，对三油酸甘油酯的活性严重降低。方法：使用磷脂酰胆碱（PC）、磷脂酰乙醇胺（PE）、磷脂酰丝氨酸（PS）、磷脂酰肌醇（PI）、溶血磷脂酰胆碱（LPC）或 Triton X-100乳化的三油酸甘油酯作为底物，分析从一名纯合LPL Arg243His患者注射肝素后获得的血浆的脂解活性。结果：患者血浆对用PC、PE、PS、PI、LPC和 Triton X-100乳化的三油酸甘油酯的水解活性分别为9.22±1.06 μmol/ml/h/ngLPL、2.94±1.60 μmol/ml/h/ng LPL、3.72±1.63 μmol/ml/h/ng LPL、3.40±1.20 μmol/ml/h/ngLPL、3.72±1.96 μmol/ml/h/ngLPL和7.80±4.48 μmol/ml/h/ng LPL。因此，用PC乳化的三油酸甘油酯测定的患者LPL的比活性显著高于用PE、PS、PI或LPC作为乳化剂时的比活性。相对于用PC、PE、PS、PI和LPC作为乳化剂测量的正常血浆活性，突变体的活性分别为49.1±5.2%、44.1±5.7%、31.7±12.6%、19.2±6.9%和23.8±11.3%。与经典乳化剂Triton X-100测量的相对活性（12.9±6.7%）相比，使用PC、PE、PS、PI和LPC作为乳化剂时，突变体对三油酸甘油酯脂解的活性相对于正常活性显著增加。结论：LPL Arg243His对三油酸甘油酯水解的损害通过用磷脂乳化三油酸甘油酯得到部分改善。使用各种磷脂乳化剂对三油酸甘油酯水解进行体外分析可能有助于进一步了解LPL功能受损情况。
