TY - JOUR
T1 - The phospholipid-binding and immunochemical properties of amidinated, guanidinated and acetylated apolipoprotein A-II
AU - Mao, Simon J.T.
AU - Sparrow, James T.
AU - Gotto, Antonio M.
AU - Jackson, Richard L.
N1 - Funding Information:
The authors gratefully acknowledge the assistance of Saundra Wrye and Debbie Mason in the preparation of the manuscript and of Kaye Shewmaker in drawing the figures. This material was developed by the Atherosclerosis, Lipids and Lipoprotein Section of the National Heart and Blood Vessel Research and Demonstration Center, Baylor College of Medicine, a grant-supported research project of the National Heart, Lung and Blood Institute, National Institutes of Health, Grant No. HL 17269 and by the American Heart Association. JTS is an American Heart Association Established Investigator.
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 1980/2/22
Y1 - 1980/2/22
N2 - To determine the importance of lysine groups in the sites for lipid-protein interaction and antigenic reactivity, reduced, carboxymethylated apoliprotein A-II and apolipoprotein A-II were modified by either amidination, guanidination or acetylation. The conformation, phospholipid-binding properties and immunochemical reactivity of each derivative were then determined. Retaining the positive charges on CM-apolipoprotein A-II by either amidination or guanidination had little or no effect on the conformation of the apoprotein; each had approximately 35% α-helical structure in the absence of dimyristoylphosphatidylcholine (DMPC) and 68% in the presence. In the absence of lipid, acetylated apolipoprotein A-II contained 17% α-helicity; the α-helicity of the protein increased to 48% in the presence of DMPC. Furthermore, each derivative formed complexes with vesicles of DMPC which are similar to that of CM-apolipoprotein A-II. The molar ratio of DMPC to protein for CM-apolipoprotein A-II, amidinated apolipoprotein A-II, guanidinated apolipoprotein A-II and acetylated apolipoprotein A-II were 43, 52, 62, and 69: 1 respectively. By quantitative radioimmunoassay, the immunoreactivity of CM-apolipoprotein A-II and its amidinated, guanidinated and acetylated derivatives were indistinguishable. Based on these results, we conclude that retaining the positive charges by amidination or guanidination or neutralizing the positive charge by acetylation does not affect the lipid-binding or immunochemical properties of apolipoprotein A-II.
AB - To determine the importance of lysine groups in the sites for lipid-protein interaction and antigenic reactivity, reduced, carboxymethylated apoliprotein A-II and apolipoprotein A-II were modified by either amidination, guanidination or acetylation. The conformation, phospholipid-binding properties and immunochemical reactivity of each derivative were then determined. Retaining the positive charges on CM-apolipoprotein A-II by either amidination or guanidination had little or no effect on the conformation of the apoprotein; each had approximately 35% α-helical structure in the absence of dimyristoylphosphatidylcholine (DMPC) and 68% in the presence. In the absence of lipid, acetylated apolipoprotein A-II contained 17% α-helicity; the α-helicity of the protein increased to 48% in the presence of DMPC. Furthermore, each derivative formed complexes with vesicles of DMPC which are similar to that of CM-apolipoprotein A-II. The molar ratio of DMPC to protein for CM-apolipoprotein A-II, amidinated apolipoprotein A-II, guanidinated apolipoprotein A-II and acetylated apolipoprotein A-II were 43, 52, 62, and 69: 1 respectively. By quantitative radioimmunoassay, the immunoreactivity of CM-apolipoprotein A-II and its amidinated, guanidinated and acetylated derivatives were indistinguishable. Based on these results, we conclude that retaining the positive charges by amidination or guanidination or neutralizing the positive charge by acetylation does not affect the lipid-binding or immunochemical properties of apolipoprotein A-II.
KW - (Human plasma)
KW - Acetylation
KW - Amidination
KW - Antigenic properties
KW - Apolipoprotein A-II
KW - Guanidination
KW - Phospholipid binding
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U2 - 10.1016/0005-2760(80)90167-8
DO - 10.1016/0005-2760(80)90167-8
M3 - Article
C2 - 6766748
AN - SCOPUS:0018851075
VL - 617
SP - 245
EP - 253
JO - Biochimica et Biophysica Acta - Lipids and Lipid Metabolism
JF - Biochimica et Biophysica Acta - Lipids and Lipid Metabolism
SN - 0005-2760
IS - 2
ER -