Method for removal of triglycerides in lipoproteins other than low-density lipoproteins
Disclosed is a method for selectively eliminating triglycerides in lipoproteins other than low density lipoprotein, which method allows one to provide a method for directly and differentially quantifying LDL-TG in a sample with excellent simplicity, specificity and accuracy using an automated analyzer or the like without performing a laborious operation of pretreatment such as centrifugation or electrophoresis. The method for eliminating triglycerides in lipoproteins other than low density lipoproteins includes allowing lipoprotein lipase, cholesterol esterase, glycerol kinase and glycerol-3-phosphate oxidase to act on a sample in the presence of a surfactant that acts on lipoproteins other than low density lipoprotein and/or a surfactant having LDL-protecting action, and eliminating hydrogen peroxide produced thereby.
1. A method for specifically qualifying triglycerides in low density lipoprotein, said method comprising:
eliminating triglycerides in non-LDL lipoproteins by allowing lipoprotein lipase, cholesterol esterase, glycerol kinase and glycerol-3-phosphate oxidase to simultaneously act on a sample in the presence of a surfactant that acts on lipoproteins other than low density lipoprotein and/or a surfactant having LDL-protecting action;
eliminating hydrogen peroxide produced thereby; and
specifically quantifying triglycerides in low density lipoprotein.
2. The method according to claim 1 , wherein said surfactant is a polyoxyalkylene derivative having a Hydrophile-Lipophile Balance (HLB) value of 13 to 15.
3. The method according to claim 2 , wherein said polyoxyalkylene derivative is a polyoxyalkylene polycyclic phenylether having an HLB value of 13 to 15.
4. The method according to claim 2 , wherein said polyoxyalkylene derivative is selected from the group consisting of polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethlene oleyl ether, polyoxyethylene higher alcohol ether, polyoxyethylene octyl phenyl ether and poly oxyethylene nonylphenyl ether.
5. The method according to claim 1 , wherein the cholesterol esterase is derived from Pseudomonas sp.
6. The method according to claim 1 , wherein said eliminating triglycerides to quantify triglycerides in low density lipoprotein further comprises a divalent metal ion selected from the group consisting of copper ion, iron ion, calcium ion and magnesium ion.
7. The method according to claim 6 , wherein said divalent metal ion is selected from the group consisting of copper ion and iron ion.
8. The method according to claim 6 , wherein said divalent metal ion is magnesium ion.
9. The method according to claim 1 , wherein the quantifying triglycerides in low density lipoprotein exhibits a correlation coefficient of 0.856 to 0.977 with a quantification measurement of triglycerides in low density lipoprotein by an ultracentrifugation method.