The proposed research will examine the mechanism of the reaction catalyzed by the enzyme Lecithin: Cholesterol Acyltransferase (LCAT). Interaction between the enzyme and high density lipoprotein (HDL), its primary substrate in vivo, will be investigated. A newly developed method involving hydrophobic chromatography will be used for the isolation of HDL. This technique avoids some of the compositional changes that are associated with other preparative techniques, particularly ultracentrifugation. The HDL will be fractionated on DEAE cellulose into subfractions which are known to exhibit differential reactivity toward LCAT. Specific phases of the proposed research will include: 1) Incubation of the HDL subfractions with purified enzyme and examination of the LCAT reaction as a function of the concentration of substrate lipids and those of specific apoprotein components of the lipid/protein substrate complex. 2) Study of the transfer of substrate lipids from triglyceride rich lipoprotein to HDL subfractions and the effect of the attendant changes on the LCAT reaction. 3) Study of the mechanism of product (lysolecithin) removal from the enzyme surface. The LCAT/HDL system has been implicated in the process called reverse cholesterol transport which facilitates the transfer of excess cholesterol from peripheral tissues to the liver. It is thus likely that the findings of the research proposed here would aid in the understanding of the reversal of atherosclerosis. Consequently, the findings may ultimately be useful in developing modalities for the prevention of cardiovascular diseases including coronary heart disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL027620-03
Application #
3339246
Study Section
Physiological Chemistry Study Section (PC)
Project Start
1984-09-01
Project End
1988-08-31
Budget Start
1986-09-01
Budget End
1988-08-31
Support Year
3
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Texas College of Osteopathic Medicine
Department
Type
Schools of Osteopathy
DUNS #
City
Fort Worth
State
TX
Country
United States
Zip Code
76107
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Kudchodkar, B J; Lee, M J; Lee, S M et al. (1988) Effect of dietary protein on cholesterol homeostasis in diabetic rats. J Lipid Res 29:1272-87
Park, M S; Kudchodkar, B J; Frohlich, J et al. (1987) Study of the components of reverse cholesterol transport in lecithin:cholesterol acyltransferase deficiency. Arch Biochem Biophys 258:545-54
Park, Y B; Yuksel, U; Gracy, R W et al. (1987) The catalytic center of lecithin:cholesterol acyltransferase: isolation and sequence of diisopropyl fluorophosphate-labeled peptides. Biochem Biophys Res Commun 143:360-3
McLeod, R; Lacko, A G; Pritchard, P H et al. (1986) Purification of biologically active apolipoproteins by chromatofocussing. J Chromatogr 381:271-83
Park, Y B; Lacko, A G (1986) Isolation and characterization of lecithin-cholesterol acyltransferase from hog plasma. Biochim Biophys Acta 877:179-90
Carlile, S I; Kudchodkar, B J; Wang, C S et al. (1986) Age-related changes in the rate of esterification of plasma cholesterol in Fischer-344 rats. Mech Ageing Dev 33:211-20
Carlile, S I; Lacko, A G (1985) Age-related changes in plasma lipid levels and tissue lipoprotein lipase activities of Fischer-344 rats. Arch Gerontol Geriatr 4:133-40
Park, Y B; Jahani, M; Lacko, A G (1985) Isolation of high-density lipoproteins by immunoaffinity column chromatography from hog plasma. Comp Biochem Physiol B 82:529-33