A novel direct homogeneous assay for ATP citrate lyase[S]

ATP citrate lyase (ACL) is a cytosolic enzyme that catalyzes the synthesis of acetyl-CoA and oxaloacetate using citrate, CoA, and ATP as substrates and Mg2+ as a necessary cofactor. The ACL-dependent synthesis of acetyl-CoA is thought to be an essential step for the de novo synthesis of fatty acids...

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Bibliographic Details
Published in:Journal of lipid research 2009-10, Vol.50 (10), p.2131-2135
Main Authors: Ma, Zhengping, Chu, Ching-Hsuen, Cheng, Dong
Format: Article
Language:English
Subjects:
acetyl-CoA
ATP Citrate (pro-S)-Lyase - metabolism
dyslipidemia
Enzyme Assays - methods
fatty acid
Humans
Methods
obesity
Reproducibility of Results
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Summary:ATP citrate lyase (ACL) is a cytosolic enzyme that catalyzes the synthesis of acetyl-CoA and oxaloacetate using citrate, CoA, and ATP as substrates and Mg2+ as a necessary cofactor. The ACL-dependent synthesis of acetyl-CoA is thought to be an essential step for the de novo synthesis of fatty acids and cholesterol. For this reason, inhibition of ACL has been pursued as a strategy to treat dyslipidemia and obesity. Traditionally, ACL enzyme activity is measured indirectly by coupling to enzymes such as malate dehydrogenase or chloramphenicol acetyl transferase. In this report, however, we describe a novel procedure to directly measure ACL enzyme activity. We first identified a convenient method to specifically detect [14C]acetyl-CoA without detecting [14C]citrate by MicroScint-O. Using this detection system, we devised a simple, direct, and homogeneous ACL assay in 384-well plate format that is suitable for high-throughput screening. The current assay consists of 1) incubation of ACL enzyme with [14C]citrate and other substrates/cofactors CoA, ATP, and Mg2+, 2) EDTA quench, 3) addition of MicroScint-O, the agent that specifically detects product [14C]acetyl-CoA, and 4) detection of signal by TopCount. This unique ACL assay may provide more efficient identification of new ACL inhibitors and allow detailed mechanistic characterization of ACL/inhibitor interactions.
ISSN:0022-2275
1539-7262
DOI:10.1194/jlr.D900008-JLR200