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)

1. The initial slopes of the substrate-activity curves of several hydrolases were determined in the microsomal and cytosolic fractions of the liver of several fish recommended by OECD for the regulatory testing of chemicals. 2. Inter-species differences ranged within a factor of 7-17 for the esterases and reached a factor of 60 for the amidase. Guppy and carp appeared endowed with hydrolase activities which, overall, are much higher than zebra fish, trout and golden orfe. 3. The comparison with the rat liver microsomal hydrolases strongly suggests that fish are endowed with similar or higher levels of A-esterase and with much less B-esterase/amidase activities.
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PMID:Xenobiotic-metabolizing enzyme systems in test fish--IV. Comparative studies of liver microsomal and cytosolic hydrolases. 135 Sep 56

The amidohydrolase superfamily comprises hundreds of hydrolytic enzymes of the (beta/alpha)8 barrel fold with mono- or binuclear active-site metal centers, and a diverse spectrum of substrates and reactions. Promiscuous activities, or cross-reactivities, between different members of the same superfamily may provide important hints regarding evolutionary and mechanistic relationships. We examined three members: dihydroorotase (DHO), phosphotriesterase (PTE), and PTE-homology protein (PHP). Of particular interest are PTE, which is thought to have evolved within the last several decades, and PHP, an amidohydrolase superfamily member of unknown function, and the closest known homologue of PTE. We found a diverse and partially overlapping pattern of promiscuous activities in these enzymes, including a significant lactonase activity in PTE, esterase activities in both PTE and PHP, and a weak PTE activity in DHO. Directed evolution was applied to improve the promiscuous esterase activities of PTE and PHP. Remarkably, the most recurrent mutation increasing esterase activity in PTE, or PHP, maps to the same location in their superposed 3D structures. The evolved variants also exhibit newly acquired promiscuous activities that were not selected for, including very weak, yet measurable, paraoxonase activity in PHP. Our results illustrate the mechanistic, structural, and evolutionary links between these enzymes, and highlight the importance of studying laboratory evolution intermediates that might resemble node intermediates along the evolutionary pathways leading to the divergence of enzyme superfamilies.
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PMID:Shared promiscuous activities and evolutionary features in various members of the amidohydrolase superfamily. 1617 87

The phosphotriesterase PTE, identified in the soil bacterium Pseudomonas diminuta, is thought to have evolved in the last several decades to degrade the pesticide paraoxon with proficiency approaching the limit of substrate diffusion (k(cat)/K(M) of 4 x 10(7)M(-1)s(-1)). It belongs to the amidohydrolase superfamily, but its evolutionary origin remains obscure. The enzyme has important potentiality in the field of the organophosphate decontamination. Recently we reported on the characterization of an archaeal member of the amidohydrolase superfamily, namely Sulfolobus solfataricus, showing low but significant and extremely thermostable paraoxonase activity (k(cat)/K(M) of 4 x 10(3)M(-1)s(-1)). Looking for other thermostable phosphotriesterases we assayed, among others, crude extracts of Sulfolobus acidocaldarius and detected activity. Since the genome of S. acidocaldarius has been recently reported, we identified there an open reading frame highly related to the S. solfataricus enzyme. The gene was cloned, the protein overexpressed in Escherichia coli, purified, and proven to have paraoxonase activity. A comparative analysis detected some significant differences between the two archaeal enzymes.
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PMID:A new phosphotriesterase from Sulfolobus acidocaldarius and its comparison with the homologue from Sulfolobus solfataricus. 1733 20

Serum paraoxonase (PON1) is well recognized for its ability to hydrolyze arylesters, toxic oxon metabolites of organophosphate insecticides and nerve agents. PON1 is a member of gene family including also PON2 and PON3; however, the later two enzymes have very limited arylesterase and practically no organophosphatase activity. We have established that all three PONs are lactonases/lactonyzing enzymes with overlapping, but also distinct substrate specificity. Dihydrocoumarin (DHC), long chain fatty acid lactones and acylhomoserine lactones (AHLs) are hydrolyzed by all three PONs and likely represent their natural substrates. The 3D structure of PON1 is a six-bladed beta-propeller containing two Ca(2+) ions necessary for the enzyme stability and enzymatic activity. Senescence marker protein (SMP30), another putative six-bladed beta-propeller, hydrolyzes DFP, sarin and soman in the presence of Mg(2+) or Mn(2+). More recently, SMP30 was characterized as a gluconolactonase with a role in vitamin C metabolism. Bacterial phosphotriesterases (PTEs) are members of the amidohydrolase superfamily and differ in their structure from the eukaryotic organophosphatases; PTEs are (beta/alpha)(8) barrels with an active site containing two transition metal ions such as Co(2+), Mn(2+) or Zn(2+). PTE from Pseudomonas diminuta hydrolyzes paraoxon extremely efficiently; this enzyme was shown to hydrolyze also DHC and other lactones. At least 3 more bacterial lactonases, dubbed PTE-like lactonases (or PLL), have been identified to possess both lactonase and organophosphatase activities. Lactones are natural compounds, many of them with high biological activity, while organophosphates are human-made chemicals introduced in the 20th century. Thus, it is plausible that lactonase is the primary activity for which the enzymes discussed here evolved for, while the organophosphatase activity arose as a promiscuous activity during their evolution. Laboratory (directed) evolution studies provided mechanisms for their catalytic versatility and demonstrated experimentally the evolvability of promiscuous enzyme functions.
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PMID:Lactonases with organophosphatase activity: structural and evolutionary perspectives. 2012 8

Recently we reported on the characterization of an archaeal member of the amidohydrolase superfamily, namely Sulfolobus acidocaldarius lactonase, showing low but significant and extremely thermostable paraoxonase activity. This enzyme, that we have named SacPox, is a member of the new described family of phosphotriesterase-like lactonases (PLLs). In this family the binuclear metal centre, which is involved in the catalytic machinery, has been poorly studied up to now. In this work we describe the expression of the protein in presence of different metals showing Mn(2+) to support the higher activity. The enzyme has been over-expressed, purified and characterized as a Mn(2+)-containing enzyme by inductive plasma coupled mass spectrometry (ICP-MS), showing also surprising kinetic differences in comparison with the cadmium-containing enzyme. The Mn(2+) containing enzyme was about 30-fold more efficient with paraoxon as substrate and more stable than the Cd(2+) counterpart, even though the Mn(2+) affinity for the binuclear metal centre is apparently lower. These results increase our knowledge of the biochemical characteristics of SacPox mainly with regard to the metal-ions modulation of function.
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PMID:Mn2+ modulates the kinetic properties of an archaeal member of the PLL family. 2317 57

With the emergence of antibiotic-resistant strains of bacteria, the available options for treating bacterial infections have become very limited, and the search for a novel general antibacterial therapy has received much greater attention. Quorum quenching can be used to control disease in a quorum sensing system by triggering the pathogenic phenotype. The interference with the quorum sensing system by the quorum quenching enzyme is a potential strategy for replacing traditional antibiotics because the quorum quenching strategy does not aim to kill the pathogen or limit cell growth but to shut down the expression of the pathogenic gene. Quorum quenching enzymes have been identified in quorum sensing and non-quorum sensing microbes, including lactonase, acylase, oxidoreductase and paraoxonase. Lactonase is widely conserved in a range of bacterial species and has variable substrate spectra. The existence of quorum quenching enzymes in the quorum sensing microbes can attenuate their quorum sensing, leading to blocking unnecessary gene expression and pathogenic phenotypes. In this review, we discuss the physiological function of quorum quenching enzymes in bacterial infection and elucidate the enzymatic protection in quorum sensing systems for host diseases and their application in resistance against microbial diseases.
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PMID:Quorum quenching enzymes and their application in degrading signal molecules to block quorum sensing-dependent infection. 2406 91

The extent to which an emerging new function trades off with the original function is a key characteristic of the dynamics of enzyme evolution. Various cases of laboratory evolution have unveiled a characteristic trend; a large increase in a new, promiscuous activity is often accompanied by only a mild reduction of the native, original activity. A model that associates weak trade-offs with "evolvability" was put forward, which proposed that enzymes possess mutational robustness in the native activity and plasticity in promiscuous activities. This would enable the acquisition of a new function without compromising the original one, reducing the benefit of early gene duplication and therefore the selection pressure thereon. Yet, to date, no experimental study has examined this hypothesis directly. Here, we investigate the causes of weak trade-offs by systematically characterizing adaptive mutations that occurred in two cases of evolutionary transitions in enzyme function: (1) from phosphotriesterase to arylesterase, and (2) from atrazine chlorohydrolase to melamine deaminase. Mutational analyses in various genetic backgrounds revealed that, in contrast to the prevailing model, the native activity is less robust to mutations than the promiscuous activity. For example, in phosphotriesterase, the deleterious effect of individual mutations on the native phosphotriesterase activity is much larger than their positive effect on the promiscuous arylesterase activity. Our observations suggest a revision of the established model: weak trade-offs are not caused by an intrinsic robustness of the native activity and plasticity of the promiscuous activity. We propose that upon strong adaptive pressure for the new activity without selection against the original one, selected mutations will lead to the largest possible increases in the new function, but whether and to what extent they decrease the old function is irrelevant, creating a bias towards initially weak trade-offs and the emergence of generalist enzymes.
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PMID:Functional Trade-Offs in Promiscuous Enzymes Cannot Be Explained by Intrinsic Mutational Robustness of the Native Activity. 2771 96

Spontaneous in vitro hatching of human blastocysts starts with the formation of a tunnel through the zona pellucida (ZP) by cellular projections of trophoblast cells. Our aim was to identify the proteins that are upregulated in these initially hatching cells as compared to trophectoderm (TE) cells from blastocysts that had not yet hatched. Forty seven women that underwent assisted reproduction treatment donated their ICSI-derived polyploid blastocysts for the study. In polyploid blastocysts that started spontaneous hatching, hatched clusters of cells were collected from the outer side of the ZP. Liquid chromatography mass spectrometry was applied to determine the proteins that were upregulated in these cells as compared to TE cells obtained from inside the ZP. Whole non-hatched polyploid blastocysts were used as controls. Overall 1245 proteins were identified in all samples. Forty nine proteins were significantly upregulated in hatching cells and 17 in the TE cells. There was minimal overlap between hatching and TE samples; only serine protease inhibitors (SERPINS) and lipocalin were detected in both samples. Myosin and actin were highly upregulated in the hatching cells as well as paraoxonase, N-acetylmuramoyl alanine amidase, and SERPINS clade A and galectin. In the TE cells, gamma butyrobetaine dioxygenase, lupus La protein, sialidase, lysosomal Pro-X carboxypeptidase, phospholipase b, and SERPINS clade B and A were among the most highly upregulated proteins. These findings may contribute to the basic knowledge of the molecular behavior of the specific cells that actively perforate the glycoprotein matrix of the ZP.
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PMID:Spontaneous in vitro hatching of the human blastocyst: the proteomics of initially hatching cells. 3319 35