Development of Sensitive Esterase Assays Based on α-Cyano-Containing Esters

Shan, Guomin; Hammock, Bruce D.

doi:10.1006/abio.2001.5388

Cited by 47 publications

(60 citation statements)

References 12 publications

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“…The activity of PME with and without EGCG on an artificial synthetic substrate with a fluorescent product was used to estimate the K i for PME interaction with EGCG. Fluorometric measurements of enzymatic degradation of cyano-acetate substrate (Shan and Hammock, 2001) showed significant reduction in purified tomato (Solanum lycopersicum L.) PME activity with the addition of EGCG (Figure 4). No background fluorescence of the cyano-acetate substrate was found in the absence of PME (data not shown), indicating the stability of this substrate in the absence of enzymatic degradation.…”

Section: Fluorometry Of Pme Interaction With Egcg Shows Reduced Enzymmentioning

confidence: 99%

Inhibition of pectin methyl esterase activity by green tea catechins

Lewis¹,

Selzer

Shahar

et al. 2008

Phytochemistry

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Section: Fluorometry Of Pme Interaction With Egcg Shows Reduced Enzymmentioning

confidence: 99%

Inhibition of pectin methyl esterase activity by green tea catechins

Lewis¹,

Selzer

Shahar

et al. 2008

Phytochemistry

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“…To evaluate the effectiveness of the use of pyrethroid-like fluorescent surrogates as predictive tools for the quantification of pyrethroid hydrolysis capacity, recombinant and authentic human carboxylesterases were evaluated against a series of fluorescent compounds that have been synthesized in our laboratory [6,8,10]. Fluorescent substrates containing pyrethroid acids (3 to 8) were hydrolyzed by hCE-1 and hCE-2 at rates that were 100-to 1000-fold slower than those with simple acids such as acetic acid and butanoic acid (1 and 2) ( Table 3), suggesting that the ability of the pyrethroid acids to access the active pocket is reduced.…”

Section: Characterization Of Human Carboxylesterases With Fluorescentmentioning

confidence: 99%

“…, cis-A7, trans-A7, A8, and four fenvalerate isomers (αR)(2R)-B5, (αR)(2S)-B5, (αS)(2R)-B5, and (αS)(2S)-B5) were all previously synthesized in this laboratory [6,[8][9][10][11]. The term α refers to the α-carbon of the alcohol moiety and 2 refers to the 2-position carbon of the acid moiety.…”

Section: Chemicalsmentioning

confidence: 99%

“…The use of α-cyanoalcoholsas a reporter system offers substantial advantages in the analysis of several enzymes including cytochrome P450s [25], epoxide hydrolases [26] and, as illustrated here, esterases such as hCE-1 and hCE-2. These advantages include high quantum yield, very large Stokes' shifts, low background, hydrolytic stability, and flexibility of structure.To evaluate the effectiveness of the use of pyrethroid-like fluorescent surrogates as predictive tools for the quantification of pyrethroid hydrolysis capacity, recombinant and authentic human carboxylesterases were evaluated against a series of fluorescent compounds that have been synthesized in our laboratory [6,8,10]. Fluorescent substrates containing pyrethroid acids (3 to 8) were hydrolyzed by hCE-1 and hCE-2 at rates that were 100-to 1000-fold slower than those with simple acids such as acetic acid and butanoic acid (1 and 2) ( Table 3), suggesting that the ability of the pyrethroid acids to access the active pocket is reduced.…”

mentioning

confidence: 99%

“…To test this hypothesis, recombinant hCE-1 and hCE-2 were produced using the baculovirus expression vector system. In addition, fluorescent surrogates that structurally resemble pyrethroids [8] were synthesized to facilitate the measurement of esterase-mediated ester hydrolysis. The hydrolysis activities of recombinant hCE-1 and hCE-2 for authentic pyrethroids and the pyrethroid-like fluorescent surrogates were determined.…”

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Characterization of pyrethroid hydrolysis by the human liver carboxylesterases hCE-1 and hCE-2

Nishi

Huang

Kamita

et al. 2006

Archives of Biochemistry and Biophysics

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105

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Carboxylesterases hydrolyze a large array of endogenous and exogenous ester-containing compounds, including pyrethroid insecticides. Herein, we report the specific activities and kinetic parameters of human carboxylesterase (hCE)-1 and hCE-2 using authentic pyrethroids and pyrethroid-like, fluorescent surrogates. Both hCE-1 and hCE-2 hydrolyzed type I and II pyrethroids with strong stereoselectivity. For example, the trans-isomers of permethrin and cypermethrin were hydrolyzed much faster than corresponding cis-counterparts by both enzymes. Kinetic values of hCE-1 and hCE-2 were determined using cypermethrin and 11 stereoisomers of the pyrethroid-like, fluorescent surrogates. K m values for the authentic pyrethroids and fluorescent surrogates were in general lower than those for other ester-containing substrates of hCEs. The pyrethroid-like, fluorescent surrogates were hydrolyzed at rates similar to the authentic pyrethroids by both enzymes, suggesting the potential of these compounds as tools for high throughput screening of esterases that hydrolyze pyrethroids. KeywordsCarboxylesterase; Pyrethroid; Fluorescent substrate Synthetic pyrethroid insecticides represented about 17% of the global pesticide market in 2002 [1]. In the coming years, the use of pyrethroids is predicted to further increase with the phase out of the use of organophosphorus insecticides. Additionally, due to the emergence and reemergence of mosquito-vectored diseases such as West Nile fever, Japanese encephalitis, and dengue fever, pyrethroids are being used with increased frequency against adult mosquitoes * Corresponding author. Fax: +1 530 752 1537.E-mail address: bdhammock@ucdavis.edu (B.D. Hammock). NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript [2]. Because of the increased agricultural and residential usage of pyrethroids, human exposure to these compounds is also expected to increase.Pyrethroids are ester-containing compounds consisting of various acid and alcohol moieties. Type I pyrethroids are esters of primary alcohols, whereas type II pyrethroids are esters of secondary alcohols that contain a cyano group at the α-carbon of the alcohol moiety. Chiral centers can exist in both the acid and alcohol moieties, leading to the existence of several stereoisomers for each pyrethroid. Ester hydrolysis by carboxylesterases and oxidation by cytochrome P450s are the main detoxification routes of pyrethroids in animals [3]. Differences in the activities of carboxylesterases and P450s between mammals and insects contribute to the low mammalian toxicity of pyrethroids (i.e., pyrethroids are metabolized faster in mammals than in insects) [3]. In general, whole animals or liver microsomes have been used to study pyrethroid metabolism in mammals, and little has been done to identify the specific carboxylesterase isozymes that hydrolyze pyrethroids [4]. Butte and Kemper [5]have shown ester-hydrolytic activities in human serum using pyrethroid-like colorimetric substrates that are not hydrolyzed by acylesterase, ...

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Lewis Acid–Lewis Base‐Catalysed Enantioselective Addition of α‐Ketonitriles to Aldehydes

Lundgren¹,

Wingstrand²,

Moberg³

2007

Adv Synth Catal

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Additions of structurally diverse a-ketonitriles to aromatic and aliphatic prochiral aldehydes yielding highly enantioenriched acylated cyanohydrins were achieved using a combination of a titanium salen dimer and an achiral or chiral Lewis base. In most cases high yields and high enantioselectivities were observed. The ee was moderate in the initial part of the reaction but increased over time. This could be avoided, and higher ees obtained, by keeping the titanium complex, in the presence or absence of aldehyde and ketonitrile, at À40 8C prior to the addition of the Lewis base. A mechanism initiated by nucleophilic attack of the tertiary amine at the carbonyl carbon atom of the ketonitile is supported by 13 C labelling experiments.

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Development of Sensitive Esterase Assays Based on α-Cyano-Containing Esters

Cited by 47 publications

References 12 publications

Inhibition of pectin methyl esterase activity by green tea catechins

Inhibition of pectin methyl esterase activity by green tea catechins

Characterization of pyrethroid hydrolysis by the human liver carboxylesterases hCE-1 and hCE-2

Lewis Acid–Lewis Base‐Catalysed Enantioselective Addition of α‐Ketonitriles to Aldehydes

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