Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sialate 9(4)-O-acetylesterases (EC 3.1.1.53) have been isolated from equine liver, bovine brain and influenza C virus. In this latter case, the esterase represents the receptor-destroying enzyme of the virus. The kinetic properties of these enzymes were determined with Neu5,9Ac2 and in part with 4-methylumbelliferyl acetate and Neu5,9Ac2-lactose. The Km values vary between 0.13 and 24 mM and the Vmax values from 0.55 to 11 U/mg of protein. The pH optima are in the range of 7.4-8.5, the molecular masses at 56,500 and 88,000 Da. In addition to a fast hydrolysis found for aromatic acetates, such as 4-methylumbelliferyl acetate or 4-nitrophenyl acetate, N-acetyl-9-O-acetylneuraminic acid is de-O-acetylated at the highest relative rate. Other substituents at the 9-position, such as lactoyl residues, or acetyl groups at other positions within the side chain are not hydrolyzed. Neu4,5Ac2, however, is a substrate for all 3 enzymes. The hydrolysis rates of this ester function, which renders sialic acids resistant to the action of sialidases, vary from 3 to 100% relative to Neu5,9Ac2. Whereas Neu5,9Ac2-lactose is hydrolyzed by the bovine and viral esterases, other O-acetylated sialic acids in glycoconjugates are only attacked by the enzyme from influenza C virus and not by that from bovine brain. The esterase from horse liver also releases 4-O-acetyl groups from equine submandibular gland mucin. By incubation with appropriate substrates and inhibition studies, carboxylesterase, amidase and choline esterase activities were excluded, as well as the cleavage of other acyls, e.g., butyryl groups. Thus, the enzymes investigated belong to the acetylesterases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sialate O-acetylesterases: key enzymes in sialic acid catabolism. 314 20

Hemagglutinin from influenza virus A is a S-palmitoylated lipoglycoprotein in which the lipid groups are thought to influence the interaction between cell membrane and capsid during budding of viral offspring as well as fusion processes of the viral membrane with the endosome after entry of the viral particle into the cell. The paper describes the development of a method for the synthesis of characteristic lipidated hemagglutinin derived peptides which additionally carry the fluorescent 7-nitrobenz-2oxa-1,3-diazole (NBD) group. To achieve this goal the enzyme-sensitive para-phenylacetoxybenzyloxycarbonyl (PAOB) ester was developed. It is cleaved from the peptides and lipidated peptides under very mild conditions and with complete selectivity by treatment with the enzyme penicillin G acylase; this results in the formation of a phenolate. This intermediate spontaneously undergoes fragmentation thereby releasing the desired carboxylates. The combined use of this enzyme-labile fragmenting ester with the acid-labile Boc group, the Pd(0)-sensitive allyl ester and the corresponding Aloc urethane gave access to a mono-S-palmitoylated and a doubly S-palmitoylated NBD-labelled hemagglutinin peptide. The binding of these lipopeptides to model membranes was analyzed in a biophysical setup monitoring the transfer of fluorescent-labelled lipopeptide from vesicles containing the non-exchangeable fluorescence quencher Rho-DHPE to quencher-free vesicles. The experiments demonstrate that one lipid group is not sufficient for quasi-irreversible membrane insertion of lipidated peptides. This is, however, achieved by introduction of the bis-palmitoyl anchor. The intervesicle transfer always implies release of peptides localized at the outer face of the vesicles into solution followed by diffusion to and insertion into acceptor vesicles. For peptides bound at the inner face of the vesicle membrane, however, an additional flip-flop diffusion to the outer face has to occur beforehand. The kinetics of these processes were estimated by fast chemical quench of the outside fluorophores by sodium dithionite.
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PMID:Synthesis and membrane binding properties of a lipopeptide fragment from influenza virus a hemagglutinin. 1220 17

Carboxylesterases metabolize numerous exogenous and endogenous ester-containing compounds including the chemotherapeutic agent CPT-11, anti-influenza viral agent oseltamivir, and many agrochemicals. Trifluoromethyl ketone (TFK)-containing compounds with a sulfur atom beta to the ketone moiety are some of the most potent carboxylesterase and amidase inhibitors identified to date. This study examined the effects of alkyl chain length (i.e., steric effects) and sulfur oxidation state upon TFK inhibitor potency (IC50) and binding kinetics (k(i)). The selective carboxylesterase inhibitor benzil was used as a non-TFK containing control. These effects were examined using two commercial esterases (porcine and rabbit liver esterase) and two human recombinant esterases (hCE-1 and hCE-2) as well as human recombinant fatty acid amide hydrolase (FAAH). In addition, the inhibition mechanism was examined using a combination of 1H NMR, X-ray crystallography, and ab initio calculations. Overall, the data show that while sulfur oxidation state profoundly affects both inhibitor potency and binding kinetics, the steric effects dominate and override the contributions of sulfur oxidation. In addition, the data suggest that inclusion of a sulfur atom beta to the ketone contributes an increase (approximately 5-fold) in inhibitor potency due to effects upon ketone hydration and/or intramolecular hydrogen bond formation. These results provide further information on the nature of the TFK binding interaction and will be useful in increasing our understanding of this basic biochemical process.
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PMID:Influence of sulfur oxidation state and steric bulk upon trifluoromethyl ketone (TFK) binding kinetics to carboxylesterases and fatty acid amide hydrolase (FAAH). 1802 88

The carboxylic group responsible for the gastric side-effects of the propionic acid derivative, flurbiprofen, was masked temporarily to overcome these side-effects and to accomplish colon-specific delivery of the drug. An amide prodrug (FLU-GLY) was synthesized by coupling flurbiprofen with L-glycine. Confirmation and characterization of the structure of the synthesized prodrug included elemental analysis, Fourier transform (FT)-IR, FT-NMR, mass (FAB) spectroscopy, and determinations of R(f), R(t) and R(M) values, respectively. Aqueous solubility and lipophilicity (logP) value were determined at pH 1.2, 4.0, 6.8 and 7.4. In-vitro reversion of FLU-GLY to flurbiprofen was measured at different pHs and in a simulated colonic environment. Acute toxicity and ulceration potential were evaluated in-vivo in albino rats. Pre-formulation studies showed increased hydrophilicity but a non-significant increase in lipophilicity of the prodrug. In-vitro reversion studies suggested that the prodrug remained intact until colonic pH was attained, when the colonic microfloral enzymes (amidase) hydrolysed the FLU-GLY amide linkage, releasing the free drug. In-vivo evaluation indicated that the prodrug was much less toxic and had less ulcerogenic activity than the parent drug. Selective delivery of drugs to the colon can be useful in terms of reducing the dose administered and reducing undesirable side-effects.
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PMID:Optimizing delivery of flurbiprofen to the colon using a targeted prodrug approach. 1841 37

Human antibody light chains belonging to subgroup II of germ line genes were amplified by a seminested PCR technique using B-lymphocytes taken from a human adult infected with influenza virus. Each gene of the human light chains was transferred into the Escherichia coli system. The recovered light chain was highly purified using a two-step purification system. Light chain 22F6 showed interesting catalytic features. The light chain cleaved a peptide bond of synthetic peptidyl-4-methyl-coumaryl-7-amide (MCA) substrates, such as QAR-MCA and EAR-MCA, indicating amidase activity. It also hydrolyzed a phosphodiester bond of both DNA and RNA. From the analysis of amino acid sequences and molecular modeling, the 22F6 light chain possesses two kinds of active sites as amidase and nuclease in close distances. The 22F6 catalytic light chain could suppress the infection of influenza virus type A (H1N1) of Madin-Darby canine kidney cells in an in vitro assay. In addition, the catalytic light chain clearly inhibited the infection of the influenza virus of BALB/c mice via nasal administration in an in vivo assay. In the experiment, the titer in the serum of the mice coinfected with the 22F6 light chain and H1N1 virus became considerably lowered compared with that of 22F6-non-coinfected mice. Note that the catalytic light chain was prepared from human peripheral lymphocyte and plays an important role in preventing infection by influenza virus. Considering the fact that the human light chain did not show any acute toxicity for mice, our procedure developed in this study must be unique and noteworthy for developing new drugs.
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PMID:Biochemical features of a catalytic antibody light chain, 22F6, prepared from human lymphocytes. 2367 96

In cells, asparagine/N-linked glycans are added to glycoproteins cotranslationally, in an attachment process that supports proper folding of the nascent polypeptide. We found that following pruning of N-glycan by the amidase PNGase F, the principal influenza vaccine antigen and major viral spike protein hemagglutinin (HA) spontaneously reattached N-glycan to its de-N-glycosylated positions when the amidase was removed from solution. This reaction, which we term N-glycanation, was confirmed by site-specific analysis of HA glycoforms by mass spectrometry prior to PNGase F exposure, during exposure to PNGase F, and after amidase removal. Iterative rounds of de-N-glycosylation followed by N-glycanation could be repeated at least three times and were observed for other viral glycoproteins/vaccine antigens, including the envelope glycoprotein (Env) from HIV. Covalent N-glycan reattachment was nonenzymatic as it occurred in the presence of metal ions that inhibit PNGase F activity. Rather, N-glycanation relied on a noncovalent assembly between protein and glycan, formed in the presence of the amidase, where linearization of the glycoprotein prevented this retention and subsequent N-glycanation. This reaction suggests that under certain experimental conditions, some glycoproteins can organize self-glycan addition, highlighting a remarkable self-assembly principle that may prove useful for re-engineering therapeutic glycoproteins such as influenza HA or HIV Env, where glycan sequence and structure can markedly affect bioactivity and vaccine efficacy.
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PMID:Spontaneous Glycan Reattachment Following N-Glycanase Treatment of Influenza and HIV Vaccine Antigens. 3191 36