Association of Plasma Lecithin: Cholesterol Acyltransferase with Plasma Lipoproteins

Abstract

Association of lecithin: cholesterol acyltransferase (LCAT) with high density lipoproteins (HDL) was investigated using HDL-Sepharose chromatography and Sephadex G-200 gel chromatography. LCAT associated to HDL-Sepharose was dissociated by the reduction of ionic strength in the elution buffer. When fresh human plasma was gel-filtered through Sephadex G-200 in the absence of NaCl, the peak of LCAT activities was separated from that of HDL. The peak of LCAT shifted to that of HDL in the buffer containing 0.14 M NaCl. The incubation study of fresh plasma at 37°C demonstrated no enzyme reaction proceeded in the absence of NaCl. From these findings we conclude that a certain amount of ionic strength is indispensable to the association of LCAT to HDL and the LCAT reaction on HDL.