Falcon (Edison Scientific) deep research report: rat Ces2c (UniProt O70631), acylcarnitine/carboxylesterase hydrolase
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Ces2c is a type-B carboxylesterase / serine hydrolase that hydrolyzes ester, thioester, amide and carbamate bonds, consistent with the acylcarnitine hydrolase and carboxylesterase activity annotations.
"Carboxylesterases (CES) are **serine hydrolases** (α/β-hydrolase fold) that catalyze hydrolysis of **ester, thioester, amide, and carbamate** bonds in endogenous lipids and xenobiotics, contributing to detoxification and prodrug activation."
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The catalytic mechanism is the canonical CES Ser-His-Glu catalytic triad with an oxyanion hole, consistent with the alpha/beta-hydrolase fold and the active-site serine annotated for O70631.
"Mechanistically, CES enzymes use a **Ser–His–Glu catalytic triad** and an **oxyanion hole** (stabilized by conserved glycine residues) to form and resolve a tetrahedral intermediate during hydrolysis."
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Acylcarnitine hydrolase activity (EC 3.1.1.28) is recognized within the rat carboxylesterase system, consistent with the UniProt acylcarnitine hydrolase assignment for O70631, though direct rat Ces2c kinetics were not retrieved.
"Historical rat esterase literature recognizes **acylcarnitine hydrolase activity (EC 3.1.1.28)** as part of the broader hepatic carboxylesterase/ester hydrolase system (with multiple isoenzymes). This is consistent with UniProt O70631 being annotated as “acylcarnitine hydrolase.”"
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CES enzymes hydrolyze diverse lipid esters including retinyl esters, supporting the retinyl-palmitate esterase activity and retinoid metabolic process annotations.
"CES enzymes collectively hydrolyze diverse lipid esters and xenobiotic esters (e.g., retinyl esters, phorbol diesters, platelet-activating factor, phthalate diesters, and multiple drugs), with major activity in liver and also in extrahepatic tissues depending on isoform."
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CES2 is monomeric in the endoplasmic reticulum and CES enzymes are recovered in microsomal fractions, supporting the ER / intracellular membrane-bounded organelle localization annotations.
"CES2 (the family context relevant to rat Ces2c) is described as **monomeric in the ER** (endoplasmic reticulum), and CES enzymes are commonly studied in **microsomal** fractions (reflecting ER association), although some preparations show both microsomal and cytosolic activity."
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CES enzymes are synthesized into the ER lumen and recovered in microsomal preparations, reinforcing the endoplasmic reticulum subcellular localization.
"CES enzymes are synthesized into the **ER lumen** and are often recovered in **microsomal** preparations, consistent with ER association."
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Comparative species data indicate rat CES2 is concentrated in small intestine and essentially undetectable in rat liver, kidney and lung, which qualifies the UniProt liver/stomach/kidney tissue-specificity statement.
"A comparative species/tissue distribution table reports that **rat CES2** is strongly expressed in **small intestine** and is essentially **undetectable in rat liver, kidney, and lung**, in contrast to humans (CES2 strongly intestinal but detectable in liver) and mice (broader CES2 expression including liver)."