Abstract:-This review covers current developments in molecular-based studies of the structure and function of carboxylesterases. To allay the confusion of the classic classification of carboxylesterase isozymes, we have proposed a novel nomenclature and classification of mammalian carboxylesterases on the basis of molecular properties. In addition, mechanisms of regulation of gene expression of carboxylesterases by xenobiotics, and involvement of carboxylesterase in drug metabolism are also described.
“…4 A) and consistent with the decrease observed upon culturing in the presence of tunicamycin. These results unequivocally confirmed that the two previously described putative glycosylation sites of hCES2 [26] are in fact glycosylated. Fig.…”
Section: Resultssupporting
confidence: 88%
“…Moreover they have different genetic variants resulting from alternative splicing, single nucleotide polymorphisms (SNPs) and multiple copy variants that have been shown to influence drug metabolism and clinical outcomes [16] , [23] . Human CES enzymes encompass a signal peptide of approximately 17 to 22 aminoacid residues responsible for their targeting to the endoplasmic reticulum (ER) where they are retained due to a carboxy-terminal ER retention signal – the H-X-E-L (Histidine – X – Glutamic Acid – Leucine) consensus sequence that interacts with the KDEL (Lysine – Aspartic Acid – Glutamic Acid – Leucine) receptor present in the luminal side of the ER [26] . This is in accordance with the absence of CES from human plasma, contrary to what happens in most rodents [1] , [25] .…”
Section: Introductionmentioning
confidence: 99%
“…While hCES1 is so far the only human CES form that has a fully known structure [2] , the tertiary structure of hCES2 has been elusive to many scientists for more than a decade. hCES2 has two potential N-glycosylation sites, at Asn103 and Asn267 [26] . The purified native human enzyme has been shown to be sensitive to endoglycosidase H (Endo H), which hydrolyzes Asn-linked high mannose oligosaccharides [21] .…”
Human carboxylesterase 2 (hCES2) is a glycoprotein involved in the metabolism of drugs and several environmental xenobiotics, whose crystallization has been proved to be a challenging task. This limitation could partly be due to glycosylation heterogeneity and has delayed the disclosure of the 3D structure of hCES2 which would be of upmost relevance for the development of new substrates and inhibitors. The present work evaluated the involvement of glycans in hCES2 activity and thermo stability in an attempt to find alternative active forms of the enzyme that might be adequate for structure elucidation.Partial or non-glycosylated forms of a secreted form of hCES2 have been obtained by three approaches: (i) enzymatic deglycosylation with peptide N-glycosidase F; (ii) incubation with the inhibitor tunicamycin; ii) site directed mutagenesis of each or both N-glycosylation sites.Deglycosylated protein did not show a detectable decrease in enzyme activity. On the other hand, tunicamycin led to decreased levels of secreted hCES2 but the enzyme was still active. In agreement, mutation of each and both N-glycosylation sites led to decreased levels of secreted active hCES2. However, the thermostability of the glycosylation mutants was decreased.The results indicated that glycans are involved, to some extent in protein folding in vivo, however, removal of glycans does not abrogate the activity of secreted hCES2.
“…4 A) and consistent with the decrease observed upon culturing in the presence of tunicamycin. These results unequivocally confirmed that the two previously described putative glycosylation sites of hCES2 [26] are in fact glycosylated. Fig.…”
Section: Resultssupporting
confidence: 88%
“…Moreover they have different genetic variants resulting from alternative splicing, single nucleotide polymorphisms (SNPs) and multiple copy variants that have been shown to influence drug metabolism and clinical outcomes [16] , [23] . Human CES enzymes encompass a signal peptide of approximately 17 to 22 aminoacid residues responsible for their targeting to the endoplasmic reticulum (ER) where they are retained due to a carboxy-terminal ER retention signal – the H-X-E-L (Histidine – X – Glutamic Acid – Leucine) consensus sequence that interacts with the KDEL (Lysine – Aspartic Acid – Glutamic Acid – Leucine) receptor present in the luminal side of the ER [26] . This is in accordance with the absence of CES from human plasma, contrary to what happens in most rodents [1] , [25] .…”
Section: Introductionmentioning
confidence: 99%
“…While hCES1 is so far the only human CES form that has a fully known structure [2] , the tertiary structure of hCES2 has been elusive to many scientists for more than a decade. hCES2 has two potential N-glycosylation sites, at Asn103 and Asn267 [26] . The purified native human enzyme has been shown to be sensitive to endoglycosidase H (Endo H), which hydrolyzes Asn-linked high mannose oligosaccharides [21] .…”
Human carboxylesterase 2 (hCES2) is a glycoprotein involved in the metabolism of drugs and several environmental xenobiotics, whose crystallization has been proved to be a challenging task. This limitation could partly be due to glycosylation heterogeneity and has delayed the disclosure of the 3D structure of hCES2 which would be of upmost relevance for the development of new substrates and inhibitors. The present work evaluated the involvement of glycans in hCES2 activity and thermo stability in an attempt to find alternative active forms of the enzyme that might be adequate for structure elucidation.Partial or non-glycosylated forms of a secreted form of hCES2 have been obtained by three approaches: (i) enzymatic deglycosylation with peptide N-glycosidase F; (ii) incubation with the inhibitor tunicamycin; ii) site directed mutagenesis of each or both N-glycosylation sites.Deglycosylated protein did not show a detectable decrease in enzyme activity. On the other hand, tunicamycin led to decreased levels of secreted hCES2 but the enzyme was still active. In agreement, mutation of each and both N-glycosylation sites led to decreased levels of secreted active hCES2. However, the thermostability of the glycosylation mutants was decreased.The results indicated that glycans are involved, to some extent in protein folding in vivo, however, removal of glycans does not abrogate the activity of secreted hCES2.
“…Several insect gene families are supposed to be associated with detoxification function, including ATP-binding cassette (ABC) (Koenig et al, 2015), Carboxyl esterase (CES) (Satoh and Hosokawa, 2009), Cytochrome P450 (CYP) (Zhu et al, 2013), Glutathione S-transferase (GST) (Hayes and Pulford, 2008), UDP-glucuronosyl transferase (UGT) (Bock, 2016), Aldehyde Oxidase (AOX) (Chang et al, 2010), Chitinase Acidic (CHIA) (Downing et al, 2000), Epoxide Hydrolase (EPHX) (Iarmarcovai et al, 2008), PIF1 5′-to-3′ DNA helicase (PIF) (Erlandson 2009), Patched Domain Containing (PTCHD) and Protein Tyrosine Phosphatase (PTP) (Herraiz et al, 2006) gene families. Here, we scanned all of these genes or gene families to detect expanded detoxification-related genes ( Fig.…”
Section: Comparative Genomics Revealed the Possible Genetic Basis Of mentioning
The fall armyworm (FAW), Spodoptera frugiperda, is a destructive pest native to America and has recently become an invasive insect pest in China. Because of its rapid spread and great risks in China, understanding of FAW genetic background and pesticide resistance is urgent and essential to develop effective management strategies. Here, we assembled a chromosome-level genome of a male FAW (SFynMstLFR) and compared re-sequencing results of the populations from America, Africa, and China. Strain identification of 163 individuals collected from America, Africa and China showed that both C and R strains were found in the American populations, while only C strain was found in the Chinese and African populations. Moreover, population genomics analysis showed that populations from Africa and China have close relationship with significantly genetic differentiation from American populations. Taken together, FAWs invaded into China were most likely originated from Africa. Comparative genomics analysis displayed that the cytochrome p450 gene family is extremely expanded to 425 members in FAW, of which 283 genes are specific to FAW. Treatments of Chinese populations with twenty-three pesticides showed the variant patterns of transcriptome profiles, and several detoxification genes such as AOX, UGT and GST specially responded to the pesticides. These findings will be useful in developing effective strategies for management of FAW in China and other invaded areas.
“…Human carboxylesterases 1 (hCE1) is one of the most abundant CEs in human, which is predominantly existed in the liver tissue [3]. In human body, hCE1 has been reported responsible for the biotransformation of a large number of structurally diverse of endogenous substrates and participated in several physiological processes, such as cholesterol hydrolysis and fatty acid metabolism [4][5][6][7]. The hydrolase activity of hCE1 may be effective in hydrolysis cholesterol ester of macrophage and relate with the formation of atherosclerosis [8,9].…”
Human carboxylesterases 1 (hCE1), one of the most important human drug metabolizing enzymes, catalyzes the hydrolysis of a large number of structurally diverse of endogenous and exogenous substrates. However, a practical, reliable and sensitive method for the precise measurement of hCE1 activities in complex biological samples has been rarely reported. In this study, a liquid chromatography-fluorescence detection (LC-FD) based method was developed for highly selective and sensitive measurement of hCE1 activities in human tissue and cell preparations. This method was based on the fluorimetric detection of HMBT, the hydrolyzed product of BMBT which was a newly developed specific probe substrate for hCE1. The developed LC-FD method was fully validated in terms of specificity, sensitivity, linearity, precision, recovery and stability. With the help of LC separation, most polar endogenous compounds in biological samples could be eluted in the column dead time, which is very beneficial for accurate determination of hCE1 activities in complex biological samples. The lower limit of quantification for HMBT (product of hCE1) of this LC-FD based method was as low as 20nM, which was quite lower than other reported methods. The method also exhibited good precision, both intra- and inter- assay variances were both lower than 2.5%. Furthermore, the newly developed method was successfully applied to measure hCE1 activity in human liver preparations from individual donors (n=12), as well as in homogenates from eleven different human cell lines. All these findings combined with this practical method are very helpful for the deep understanding of the expression and function of hCE1 in human biological samples.
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