| Modulation of the positional specificity of lecithin-cholesterol acyltransferase by the acyl group composition of its phosphatidylcholine substrate: role of the sn-1-acyl group. | |
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MedLine Citation:
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PMID: 9753449 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Human lecithin-cholesterol acyltransferase (LCAT), which is normally specific for the sn-2 position of phosphatidylcholine (PC), derives a significant percentage of acyl groups from the sn-1 position, when sn-2 is occupied by 18:0, 20:4, or 22:6. We investigated the relative importance of the two acyl groups of PC in determining the positional specificity by first analyzing the cholesteryl esters formed in the presence of symmetric PCs labeled at sn-2. Both human and rat LCATs transferred exclusively the sn-2-acyl group from all symmetric PCs, including 18:0-18:0, and 20:4-20:4, showing that the presence of these fatty acids at sn-2 does not automatically alter the positional specificity. The role of the sn-1-acyl group was then tested by using PCs containing 20:4 or 18:0 at sn-2 and fatty acids of various chain lengths and unsaturation at sn-1. With 20:4 at sn-2 and saturated fatty acids of various chain lengths at sn-1, human and rat LCATs derived, respectively, 5-72% and 1-20% of the total acyl groups from the sn-1 position. However, the chain length of the sn-1-acyl did not correlate with its utilization by either enzyme. Various unsaturated fatty acids at sn-1 also were transferred by human LCAT at a higher rate (5-75% of total) than they were transferred by rat LCAT (0-21%). With sn-2-18:0 PCs, however, rat LCAT exhibited greater alteration in positional specificity (30-95% from sn-1) than human LCAT (15-83% from sn-1). These results show that while the primary determinant of positional specificity is the sn-2-acyl group of PC, the structure of sn-1-acyl significantly modifies it. |
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Authors:
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M Liu; V S Subramanian; P V Subbaiah |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Biochemistry Volume: 37 ISSN: 0006-2960 ISO Abbreviation: Biochemistry Publication Date: 1998 Sep |
Date Detail:
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Created Date: 1998-10-28 Completed Date: 1998-10-28 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0370623 Medline TA: Biochemistry Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 13626-33 Citation Subset: IM |
Affiliation:
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Departments of Medicine and Biochemistry, Rush Medical College, Chicago, Illinois 60612, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Acylation Animals Cholesterol / chemistry, metabolism Cholesterol Esters / chemistry, metabolism Fatty Acids / chemistry, metabolism Humans Isomerism Lysophosphatidylcholines / chemistry*, metabolism Phosphatidylcholine-Sterol O-Acyltransferase / chemistry*, metabolism Rats Substrate Specificity |
| Grant Support | |
ID/Acronym/Agency:
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HL 52597/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Cholesterol Esters; 0/Fatty Acids; 0/Lysophosphatidylcholines; 57-88-5/Cholesterol; EC 2.3.1.43/Phosphatidylcholine-Sterol O-Acyltransferase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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