The

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

carboxylesterase (or carboxylic-ester hydrolase, EC 3.1.1.1; systematic name carboxylic-ester hydrolase)

catalyzes Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

reactions of the following form: :a

carboxylic ester In chemistry, an ester is a chemical compound, compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds c ...

+ H₂O

\rightleftharpoons

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

+ a

carboxylate In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an anion, an ion with negative charge. Carboxylate salts are salts that have the general formula , where M is a metal and ''n'' is 1, 2,... ...

Most enzymes from this group are

serine hydrolase Serine hydrolases are one of the largest known enzyme classes comprising approximately ~200 enzymes or 1% of the genes in the human proteome. A defining characteristic of these enzymes is the presence of a particular serine at the active site, whic ...

s belonging to the superfamily of proteins with α/β hydrolase fold. Some exceptions include an esterase with

β-lactamase Beta-lactamases (β-lactamases) are enzymes () produced by bacteria that provide Multiple drug resistance, multi-resistance to beta-lactam antibiotics such as penicillins, cephalosporins, cephamycins, monobactams and carbapenems (ertapenem ...

-like structure (). Carboxylesterases are widely distributed in nature, and are common in mammalian liver. Many participate in

phase I metabolism Drug metabolism is the metabolic breakdown of drugs by living organisms, usually through specialized enzymatic systems. More generally, xenobiotic metabolism (from the Greek xenos "stranger" and biotic "related to living beings") is the set of ...

xenobiotics A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism. It can also cover substances that are present in much higher concentrations than are usual. Natural compo ...

such as toxins or drugs; the resulting

s are then conjugated by other enzymes to increase solubility and eventually excreted. The essential polyunsaturated fatty acid

arachidonic acid Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega−6 fatty acid 20:4(ω−6), or 20:4(5,8,11,14). It is a precursor in the formation of leukotrienes, prostaglandins, and thromboxanes. Together with omega−3 fatty acids an ...

(AA C₂₀ H₃₂ O₂; 20: 4, n-6), formed by the synthesis from dietary

linoleic acid Linoleic acid (LA) is an organic compound with the formula . Both alkene groups () are ''cis''. It is a fatty acid sometimes denoted 18:2 (n−6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid. Linoleic acid is a polyunsat ...

(LA: C₁₈H₃₂O₂ 18:2, n-6), has a role as a human carboxylesterase inhibitor. The

carboxylesterase family Carboxylesterase, type B is a family of evolutionarily related proteins that belongs to the superfamily of proteins with the Alpha/beta hydrolase fold. Higher eukaryotes have many distinct esterases. The different types include those that act on ...

of evolutionarily related proteins (those with clear

sequence homology Sequence homology is the homology (biology), biological homology between DNA sequence, DNA, RNA sequence, RNA, or Protein primary structure, protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments ...

to each other) includes a number of proteins with different substrate specificities, such as

acetylcholinesterase Acetylcholinesterase (HUGO Gene Nomenclature Committee, HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme th ...

Examples

* ali-esterase, * B-esterase, * butyrate esterase, * butyryl esterase, *

carboxylesterase 1 Liver carboxylesterase 1 also known as carboxylesterase 1 (CES1, hCE-1 or CES1A1) is an enzyme that in humans is encoded by the ''CES1'' gene. The protein is also historically known as serine esterase 1 (SES1), monocyte esterase and cholesterol es ...

carboxylesterase 2 Carboxylesterase 2 is an enzyme that in humans is encoded by the ''CES2'' gene. It is a member of the alpha/beta fold hydrolase family. Carboxylesterase 2 is a member of a large multigene family. The enzymes encoded by these genes are responsi ...

carboxylesterase 3 Carboxylesterase 3 is an enzyme that in humans is encoded by the ''CES3'' gene. Function Carboxylesterase 3 is a member of a large multigene family. The enzymes encoded by these genes are responsible for the hydrolysis of ester- and amide-bon ...

* esterase A, * esterase B, * esterase D, * methylbutyrase, * methylbutyrate esterase, * monobutyrase, * procaine esterase, * propionyl esterase, * triacetin esterase, * vitamin A esterase, and *

cocaine esterase The chloride cocaine esterase (EC 3.1.1.84, CocE, hCE2, hCE-2, human carboxylesterase 2; systematic name cocaine benzoylhydrolase) catalyses the reaction : cocaine + H2O \rightleftharpoons ecgonine methyl ester + benzoate ''Rhodococcus'' sp. s ...

The last enzyme also participates in

alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...

biosynthesis.

Genes

Humans genes that encode carboxylesterase enzymes include: * CES1 * CES2 * CES3 * CES4 * CES7 * CES8 An approved nomenclature has been established for the five mammalian carboxylesterase gene families.

Examples

Genes

References

Further reading