Long-chain polyunsaturated fatty acids in the sn-2 position of phosphatidylcholine decrease the stability of recombinant high density lipoprotein apolipoprotein A-I and the activation energy of the lecithin:cholesterol acyltransferase reaction

Parks, John S.; Gebre, Abraham K.

doi:10.1016/s0022-2275(20)37439-3

Cited by 35 publications

(29 citation statements)

References 41 publications

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“…rHDL were used as substrate particles for measurement of CE formation by LCAT as described previously (16). rHDL were made with purified human plasma apoA-I, [ 3 H]cholesterol (50,000 dpm/ g), and PC in a starting molar ratio of 1:5:80.…”

Section: Recombinant Hdl (Rhdl) Synthesis and Characterizationmentioning

confidence: 99%

“…All PC species used for the studies were characterized as described (18). In a third experiment, rHDL were made that contained 10% of the PC species containing 18 carbon sn -2 fatty acyl chains (from Study 1) and 90% OPPC ether as described previously (16). Compositional analysis of the rHDL, chemical crosslinking of apoA-I, and gradient gel electrophoresis were performed as described previously (16,19,20).…”

Section: Recombinant Hdl (Rhdl) Synthesis and Characterizationmentioning

confidence: 99%

“…LCAT incubations were performed in duplicate or triplicate as described previously (16). Assays of initial reaction velocity were performed in 0.5 ml buffer (10 m m Tris, 140 m m NaCl, 0.01% EDTA, 0.01% NaN 3 , pH 7.4) containing: rHDL (0.2 g cholesterol), 0.6% bovine serum albumin (fatty acid-free; Sigma Chemical Co.), 2 m m ␤ -mercaptoethanol, and 25-50 ng of purified human plasma LCAT, isolated as described previously (21).…”

Section: Lcat Assaysmentioning

confidence: 99%

“…Kinetic analysis of LCAT activity was performed on a subset of rHDL using substrate cholesterol concentrations ranging from 0.52 to 26 m and 50 ng of purified human plasma LCAT (21). Assays were performed in duplicate and analyzed using a nonlinear least squares program (Graph Pad Prism, San Diego, CA) to determine apparent V max and apparent K m as described previously (16).…”

Section: Lcat Assaysmentioning

confidence: 99%

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Phosphatidylcholine fluidity and structure affect lecithin:cholesterol acyltransferase activity

Parks

Huggins²,

Gebre

et al. 2000

Journal of Lipid Research

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The purpose of this study was to test the hypothesis that lipid fluidity regulates lecithin:cholesterol acyltransferase (LCAT) activity. Phosphatidylcholine (PC) species were synthesized that varied in fluidity by changing the number, type ( cis vs. trans ), or position of the double bonds in 18 or 20 carbon sn -2 fatty acyl chains and recombined with [ 3 H]cholesterol and apolipoprotein A-I to form recombinant high density lipoprotein (rHDL) substrate particles. The activity of purified human plasma LCAT decreased with PC sn -2 fatty acyl chains containing trans versus cis double bonds and as double bonds were moved towards the methyl terminus of the sn -2 fatty acyl chain. The decrease in LCAT activity was significantly correlated with a decrease in rHDL fluidity (measured by diphenylhexatriene fluorescence polarization) for PC species containing 18 carbon ( r 2 ‫؍‬ 0.61, n ‫؍‬ 18) and 20 carbon ( r 2 ‫؍‬ 0.93, n ‫؍‬ 5) sn -2 fatty acyl chains. rHDL were also made containing 10% of the 18 carbon sn -2 fatty acyl chain PC species and 90% of an inert PC ether matrix ( sn -1 18:1, sn -2 16:0 PC ether) to normalize rHDL fluidity. Even though fluidity was similar among the PC ether-containing rHDL, the order of PC reactivity with LCAT was significantly correlated ( r 2 ‫؍‬ 0.71) with that of 100% PC rHDL containing the same 18 carbon sn -2 fatty acyl chain species, suggesting that PC structure in the active site of LCAT determines reactivity in the absence of measurable differences in bilayer fluidity.We conclude that PC fluidity and structure are major regulators of LCAT activity when fatty acyl chain length is constant. -Parks,

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Section: Recombinant Hdl (Rhdl) Synthesis and Characterizationmentioning

confidence: 99%

Section: Recombinant Hdl (Rhdl) Synthesis and Characterizationmentioning

confidence: 99%

Section: Lcat Assaysmentioning

confidence: 99%

Section: Lcat Assaysmentioning

confidence: 99%

See 2 more Smart Citations

Phosphatidylcholine fluidity and structure affect lecithin:cholesterol acyltransferase activity

Parks

Huggins²,

Gebre

et al. 2000

Journal of Lipid Research

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show abstract

“…Furthermore, in vitro assays have shown that arachidonyl-CoA is a poor substrate for ACAT2 (41,46). Although LCAT is capable of synthesizing CE with long-chain PUFA, it does not use these substrates as well as 18 carbon fatty acyl substrates, apparently because the increased number of double bonds decreases the appVmax of the enzyme through some interference at the active site of LCAT (47,48). Together these observations suggest that ACAT2, which appears to be responsible for the synthesis of CEs that are secreted by the liver or intestine in chylomicron or VLDL particles, does not significantly contribute to the pool of long chain CE in plasma apoB lipoproteins.…”

Section: Discussionmentioning

confidence: 99%

In vivo contribution of LCAT to apolipoprotein B lipoprotein cholesteryl esters in LDL receptor and apolipoprotein E knockout mice

Furbee

Francone

Parks

2002

Journal of Lipid Research

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Previous studies have indicated that LCAT may play a role in the generation of cholesteryl esters (CE) in plasma apolipoprotein B (apoB) lipoproteins. The purpose of the present study was to examine the quantitative importance of LCAT on apoB lipoprotein CE fatty acid (CEFA) composition. LCAT ؊ / ؊ mice were crossed into the LDL receptor (LDLr) ؊ / ؊ and apoE ؊ / ؊ background to retard the clearance and increase the concentration of apoB lipoprotein in plasma. Plasma free cholesterol was significantly elevated but total and esterified cholesterol concentrations were not significantly affected by removal of functioning LCAT in either the LDLr ؊ / ؊ or apoE ؊ / ؊ mice consuming a chow diet. However, when functional LCAT was removed from LDLr ؊ / ؊ mice, the CEFA ratio (saturated ؉ monounsaturated/polyunsaturated) of plasma LDL increased 7-fold because of a 2-fold increase in saturated and monounsaturated CE, a 40% reduction in cholesteryl linoleate, and a complete absence of long chain ( Ͼ 18 carbon) polyunsaturated CE (20:4, 20:5n-3, and 22:6n-3), from 29.3% to 0%. Removal of functional LCAT from apoE ؊ / ؊ mice resulted in only a 1.6-fold increase in the CEFA ratio, due primarily to a complete elimination of long chain CE (7.7% to 0%). Our results demonstrate that LCAT contributes significantly to the CEFA pool of apoB lipoprotein and is the only source of plasma long chain polyunsaturated CE in these mice. -Furbee, J. W., Jr., O. Francone, and J. S. Parks. In vivo contribution of LCAT to apolipoprotein B lipoprotein cholesteryl esters in LDL receptor and apolipoprotein E knockout mice.

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Preparation, Characterizations, and In Vitro Metabolic Processes of Paclitaxel-Loaded Discoidal Recombinant High-Density Lipoproteins

Jia

Xiao

Liu

et al. 2012

Journal of Pharmaceutical Sciences

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Long-chain polyunsaturated fatty acids in the sn-2 position of phosphatidylcholine decrease the stability of recombinant high density lipoprotein apolipoprotein A-I and the activation energy of the lecithin:cholesterol acyltransferase reaction

Cited by 35 publications

References 41 publications

Phosphatidylcholine fluidity and structure affect lecithin:cholesterol acyltransferase activity

Phosphatidylcholine fluidity and structure affect lecithin:cholesterol acyltransferase activity

In vivo contribution of LCAT to apolipoprotein B lipoprotein cholesteryl esters in LDL receptor and apolipoprotein E knockout mice

Preparation, Characterizations, and In Vitro Metabolic Processes of Paclitaxel-Loaded Discoidal Recombinant High-Density Lipoproteins

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