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)

Arylacetamide deacetylation is an important enzyme activity in the metabolic activation of arylamine substrates to ultimate carcinogens, best described as a carboxylesterase/amidase type of reaction. A 7-fold variation in the Vmax of 2-acetylaminofluorene deacetylation in 24 human livers was observed. An acetylaminofluorene deacetylase was purified 90 fold from human liver microsomes by PEG-fractionation, anion exchange and hydrophobic interaction chromatography. The purified 45kD protein showed no amino acid sequence homology to other carboxylesterases, neither in its N-terminus nor in tryptic peptides. Antibodies raised against the deacetylase recognized the protein with high specificity. This report thus describes the first arylacetamide deacetylase in human liver.
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PMID:Purification and characterization of a human liver arylacetamide deacetylase. 204 31

Ochrobactrum anthropi possesses an L-aminopeptidase (DmpA) also able to act as a D-amidase/D-esterase. DmpA (40 kDa) is activated by auto-catalyzed protein splicing liberating an alpha-amino group presumably used as a general base in the catalytic mechanism. Two crystal forms were obtained at 294 K in 13-16% PEG 2000 mono-methylether at pH 9.0, adding either 0.2 M magnesium chloride or 1 M lithium chloride. Crystals of the first form belong to the space group C2221 and diffract to 3.0 A resolution, whereas crystals of the second form belong to the space group P21212 and diffract to 2.3 A resolution. Initial screening for heavy-atom derivatives on form II crystals, has led to a well substituted Hg derivative.
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PMID:Crystallization and preliminary X-ray analysis of a new L-aminopeptidase-D-amidase/D-esterase activated by a Gly-Ser peptide bond hydrolysis. 1008 74

Yields of kinetically controlled synthesis of antibiotics catalyzed by penicillin G acylase from Escherichia coli (PGA) have been greatly increased by continuous extraction of water soluble products (cephalexin) away from the surroundings of the enzyme. In this way its very rapid enzymatic hydrolysis has been avoided. Enzymes covalently immobilized inside porous supports acting in aqueous two-phase systems have been used to achieve such improvements of synthetic yields. Before the reaction is started, the porous structure of the biocatalyst can be washed and filled with one selected phase. In this way, when the pre-equilibrated biocatalyst is mixed with the second phase (where the reaction product will be extracted), the immobilized enzyme remains in the first selected phase in spite of its possibly different natural trend. Partition coefficients (K) of cephalexin in very different aqueous two-phase systems were firstly evaluated. High K values were obtained under drastic conditions. The best K value for cephalexin (23) was found in 100% PEG 600-3 M ammonium sulfate where cephalexin was extracted to the PEG phase. Pre-incubation of immobilized PGA derivatives in ammonium sulfate and further suspension with 100% PEG 600 allowed us to obtain a 90% synthetic yield of cephalexin from 150 mM phenylglycine methyl ester and 100 mM 7-amino desacetoxicephalosporanic acid (7-ADCA). In this reaction system, the immobilized enzyme remains in the ammonium sulfate phase and hydrolysis of the antibiotic becomes suppressed because of its continuous extraction to the PEG phase. On the contrary, synthetic yields of a similar process carried out in monophasic systems were much lower (55%) because of a rapid enzymatic hydrolysis of cephalexin.
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PMID:Use of aqueous two-phase systems for in situ extraction of water soluble antibiotics during their synthesis by enzymes immobilized on porous supports. 1009 16

The amidase activity of bovine pancreas trypsin in water-soluble complexes with poly(ethylene glycol)-block-poly(alpha,beta-aspartic acid) (PEG-PAA) was evaluated by a colorimetric assay using L-lysine p-nitroanilide as a substrate. The enzymatic reaction of trypsin was accelerated through the complexation with PEG-PAA. By determining the kinetic parameters of the enzymatic reaction of trypsin, it was confirmed that the catalytic rate constant of the complexed trypsin was 15 times higher than that of the native trypsin. From the evaluation of pH dependence of initial reaction rate, it was indicated that this acceleration was induced by a stabilization of the imidazolium ion of the His residue in the catalytic site, the Asp-His-Ser triad, of trypsin due to the Asp units of PEG-PAA. The hydrogen bonded Asp-His pairs are critical constituents in several key enzymatic reactions including serine protease and apurinic endonucleases, and it was expected that the acceleration of the catalytic reaction might occur for other enzymes by the formation of water-soluble complexes with PEG-PAA.
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PMID:Acceleration of enzymatic reaction of trypsin through the formation of water-soluble complexes with poly(ethylene glycol)-block-poly(alpha,beta-aspartic acid). 1576 22

Single-triggered disassemble dendrimers were recently developed and introduced as a potential platform for a multi-prodrug. These unique structural dendrimers can release all of their tail units through a self-immolative chain fragmentation initiated by a single cleavage at the dendrimer's core. There are several examples for the bioactivation of first-generation self-immolative dendritic prodrugs. However, enzymatic activation failed for second-generation self-immolative dendrimers. The hydrophobic large molecular structure of the dendritic prodrugs results in aggregation under aqueous conditions and prevented the enzyme from reaching the triggering substrate. Here we show a simple solution for the enzymatic activation of second-generation self-immolative dendrimers. Poly(ethylene glycol) (PEG) was conjugated to the dendritic platform via click chemistry. The poly(ethylene glycol) tails significantly decreased the hydrophobic properties of the dendrimers and thereby prevented aggregate formation. We designed and synthesized a dendritic prodrug with four molecules of the anticancer agent camptothecin and a trigger that can be activated by penicillin-G-amidase. The PEG5000-conjugated, self-immolative dendritic prodrug was effectively activated by penicillin-G-amidase under physiological conditions and free camptothecin was released to the reaction media. Cell-growth inhibition assays demonstrated increased toxicity of the dendritic prodrug upon incubation with the enzyme.
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PMID:Enzymatic activation of second-generation dendritic prodrugs: Conjugation of self-immolative dendrimers with poly(ethylene glycol) via click chemistry. 1710 21

The amidase reaction of trypsin, which is a member of the serine proteinase family, is accelerated by its complexation with block ionomers containing a polycarboxylate block, such as PEG-PAA, PEG-PGA, or PEG-PMA. PEG-PAA and PEG-PGA had similar effects, causing an increase in the k(cat) value and a shift in the pH profile to a lower pH region. On the other hand, PEG-PMA showed not only an increase in the k(cat) value, but also a decrease in the activation energy; however, there was no shift in the pH dependence of the initial reaction rate. Such differences might be induced by the difference in pK(a) values of the polycarboxylate block in block ionomers.
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PMID:Effect of polycarboxylate blocks on the amidase activity of trypsin through complexation with PEG/polycarboxylate block ionomers. 1737 Feb 72

Bifunctional pyrimidine deaminase/reductase (RibD) plays an important role during riboflavin biosynthesis in many microorganisms. The 40.4 kDa RibD from Shigella flexneri 2a has been cloned, expressed, purified and characterized. Three Crystals of RibD have been obtained by the hanging-drop technique at 291 K using PEG 20k or NaCl as precipitant. The RibD crystal using PEG 20k as precipitant diffracted to 2.5A.
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PMID:Cloning, expression, purification, characterization, crystallization and x-ray diffraction of bifunctional pyrimidine deaminase/reductase from Shigella flexneri 2a. 1804 36

PEGylated proteins are routinely used as therapeutics, but systematic studies of the effect of PEG molecular weight and linking chemistry on the biological activity and particularly the thermal stability of the conjugated protein are rarely made. Here, activated monomethoxypolyethylene glycol (mPEG)s (Mw 1100, 2000 and 5000 g/mol) were prepared using succinic anhydride (SA), cyanuric chloride (CC) or tosyl chloride (TC) and used to synthesise a library of trypsin conjugates. The enzyme activity (KM, Vmax and Kcat) of native trypsin and the mPEG-modified trypsin conjugates was compared using N-benzoyl-l-arginine p-nitroanilide (BAPNA) as a substrate, and their thermal stability determined using both BAPNA and N-alpha-benzoyl-l-arginine ethyl ester hydrochloride (BAEE) as substrates to measure amidase and esterase activity respectively. The effect of conjugate chemistry on trypsin autolysis was also examined at 40 degrees C. PEG-trypsin conjugates containing the higher molecular weight of mPEG (5000 g/mol) were more stable than free trypsin, and the conjugate containing CC-mPEG 5000 g/mol had the best thermal stability.
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PMID:Effect of PEG molecular weight and linking chemistry on the biological activity and thermal stability of PEGylated trypsin. 1830 89

Using monomethoxy poly(ethylene glycol) (mPEG)-trypsin conjugates we recently showed that both PEG molecular weight (1100-5000 g/mol) and linker chemistry affect the rate of protein autolysis and thermal stability. These important factors are often overlooked but they can guide the early choice of optimal polymer/chemistry for synthesis of a lead polymer therapeutic suitable for later formulation development. As we are currently developing dextrin- and semi-telechelic poly[N-(2-hydroxypropyl)methacrylamide] (ST-HPMA)-protein conjugates as new therapeutics, the aim of this study was to examine the effect of polymer on activity, autolysis and its thermal stability using trypsin conjugates as a model and compare to the data obtained for mPEG conjugates. Trypsin conjugates were first synthesized using succinoylated dextrin (Mw approximately 8000 g/mol, dextrin I; or approximately 61,000g/mol, dextrin II), and a ST-HPMA-COOH (Mw approximately 10,100g/mol). The conjugates had a trypsin content of approximately 54, 17 and 3 wt% respectively with <5% free protein. When amidase activity (K(M), V(max) and K(cat)) was determined by using N-benzoyl-L-arginine p-nitroanilide (BAPNA) as substrate, trypsin K(M) values were not altered by conjugation, but the V(max) was approximately 6-7-fold lower, and the substrate turnover rate (K(cat)) decreased by approximately 5-7-fold. The dextrin II-trypsin conjugate was more stable than the other conjugates and native trypsin at all temperatures between 30 and 70 degrees C, and also exhibited improved thermal stability in the autolysis assays at 40 degrees C.
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PMID:Dextrin-trypsin and ST-HPMA-trypsin conjugates: enzyme activity, autolysis and thermal stability. 1942 90

alpha-(N-Acetylaminomethylene)succinic acid (AAMS) amidohydrolase from Mesorhizobium loti MAFF303099, which is involved in a degradation pathway of vitamin B(6) and catalyzes the degradation of AAMS to acetic acid, ammonia, carbon dioxide and succinic semialdehyde, has been overexpressed in Escherichia coli. To elucidate the reaction mechanism based on the tertiary structure, the recombinant enzyme was purified and crystallized by the sitting-drop vapour-diffusion method using PEG 8000 as precipitant. A crystal of the enzyme belonged to the monoclinic space group C2, with unit-cell parameters a = 393.2, b = 58.3, c = 98.9 A, beta = 103.4 degrees , and diffraction data were collected to 2.7 A resolution. The V(M) value and calculation of the self-rotation function suggested that three dimers with a threefold symmetry were possibly present in the asymmetric unit.
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PMID:Crystallization and preliminary X-ray analysis of AAMS amidohydrolase, the final enzyme in degradation pathway I of pyridoxine. 1965 51


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