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Results for “Plastic transforming enzyme”

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At least 19 recordsLinked to original sources

PubMed2026

Polyethylene transformation by a psychrotolerant Rhodococcus strain assessed by transcriptomics and 13C-isotope tracing.

Polyethylene is increasingly accumulating in nature, including remote places like the Arctic. While abiotic processes fragment polyethylene in situ, biotic transformation by microorganisms is assumed to occur. However, the enzymes and pathways involved remain poorly characterized. In this study, we used an in-house biobank from cold environments to screen for potential bacteria capable of degrading polyethylene by screening the strains in silico using the database PlasticDB and in vivo using a fluorescence-based assay. Using transcriptomic and proteomic analyses to identify genes in promising candidate strains that encode extracellular enzymes potentially capable of degrading PE, we selected a Rhodococcus erythropolis strain and two of its enzymes: a hypothetical protein (Hypr1) and a lipase family protein (Lip2). Expressing the candidate genes heterologously in Escherichia coli resulted in positive results in the fluorescence-based assay for polyethylene transformation. Applying 13C-labelled polyethylene for assessing and estimating polyethylene transformation and carbon assimilation, we found that R. erythropolis and both untransformed and recombinant E. coli extracellularly transformed the initially added polyethylene after 70 days. In addition, untransformed E. coli and R. erythropolis converted small, but significant amounts of polyethylene-derived carbon to carbon dioxide. The 13C-label was also traced into the bacterial biomass of R. erythropolis. Overall, our results provide evidence for biotic transformation of untreated polyethylene and suggests a hypothetical protein and a lipase family protein as two novel enzyme candidates associated with PE transformation.

Rhodococcus↗

PubMed2004

Transformation of biodegradable polyesters into cyclic oligomers under continuous flow using an enzyme-packed column.

The enzymatic degradation of typical chemically synthesized biodegradable plastics, such as poly(butylene adipate) and poly(epsilon-caprolactone), to a repolymerizable cyclic oligomer under continuous flow using an enzyme column was studied, directed towards green chemical recycling. It was confirmed that both polymers were quantitatively transformed into the corresponding cyclic oligomers by passage through the column packed with immobilized lipase from Candida antarctica (Novozym 435) at 40 degrees C using a toluene solution. Compared to the batch treatment in a flask, a short reaction time and a low reaction temperature occurred for complete transformations of the polyesters by continuous flow through the enzyme column. The degradation activity of the enzyme column was maintained for at least six months at 40 degrees C. Conceptual scheme of the continuous degradation equipment using the enzyme column.

Biocompatible Materials↗

PubMed2002

[Therapeutic potential of protein kinase CK2 modulators].

Data on the nuclear cascade of signal transduction, including protein kinase CK2 (PKCK2), transcription factor HMG14 and chromatin myosin-like proteins, are generalized with regard for the modern understanding of mechanisms of synaptic plasticity. The role of the neurospecific isoform and subunit structure of PKCK2, of the individual subunit autophosphorylation of PKCK2, of phosphorylation of substrate-proteins in the enzyme activity and of conformation transformations of chromatin is examined. Data on changes in the CK2-induced cascade and synaptic plasticity in learning, on age-related amnesia and on cognitive deficits induced by ethanol and chloridine in rat embryos are presented. The prospects for using modulators PKCK2, 4,5-di(N-methylcarbamoyl)-l-alkyl-imidazoles, as potential nootropics are discussed.

Animals↗

PubMed1979

[Dynamics of the connective tissue changes in rats in the process of tumor formation induced by ethacryl (AKR-15) plastic].

Morphological studies of the rat connective tissue around the implanted plates, made from a plastic Ethacryl (AKP-15) being employed in orthopedic stomatology, have demonstrated a gradual reduction of the proliferative activity of the connective tissue capsule fibroblasts, followed 6 months later by the appearance of diffuse and then focal proliferates in the internal layer with subsequent development of tumors. A histological assay of the collagen-formation revealed no dystrophic changes in the connective tissue characteristic of other types of blastomogenesis. The pattern of diformazane depositing, when histochemically assaying oxido-reduction enzymes, may evidence the cell damage of the connective tissue capsules around the implant in the first months of the experiment.

Acrylic Resins↗

PubMed2000

Lipase-catalyzed transformation of poly(epsilon-caprolactone) into cyclic dicaprolactone.

The enzymatic degradation and polymerization using an enzyme were carried out with respect to the establishment of a sustainable chemical recycling system for poly(epsilon-caprolactone) (PCL) which is a typical biodegradable synthetic plastic. The enzymatic transformation of PCL having an Mn of 110,000 using Candida antarctica lipase (lipase CA) in water-containing toluene at 40 degrees C afforded the corresponding cyclic dicaprolactone (DCL, 1,8-dioxacyclotetradecane-2,9-dione) in a yield of up to 97%. Thus the obtained DCL readily polymerized again using both the fresh and recovered lipase CAs.

Candida↗

PubMed1998

Role of water in plasticity, stability, and action of proteins: the crystal structures of lysozyme at very low levels of hydration.

Earlier studies involving water-mediated transformations in lysozyme and ribonuclease A have shown that the overall movements in the protein molecule consequent to the reduction in the amount of surrounding water are similar to those that occur during enzyme action, thus highlighting the relationship among hydration, plasticity, and action of these enzymes. Monoclinic lysozyme retains its crystallinity even when the level of hydration is reduced further below that necessary for activity (about 0.2 gram of water per gram of protein). In order to gain insights into the role of water in the stability and the plasticity of the protein molecule and the geometrical basis for the loss of activity that accompanies dehydration, the crystal structures of monoclinic lysozyme with solvent contents of 17.6%, 16.9%, and 9.4% were determined and refined. A detailed comparison of these forms with the normally hydrated forms show that the C-terminal segment (residues 88-129) of domain I and the main loop (residues 65-73) in domain II exhibit large deviations in atomic positions when the solvent content is reduced, although the three-dimensional structure is essentially preserved. Many crucial water bridges between different regions of the molecule are conserved in spite of differences in detail, even when the level of hydration is reduced well below that required for activity. The loss of activity that accompany dehydration appears to be caused by the removal of functionally important water molecules from the active-site region and the reduction in the size of the substrate binding cleft.

Binding Sites↗

PubMed2006

Digestive plasticity in tadpoles of the Chilean giant frog (Caudiverbera caudiverbera): factorial effects of diet and temperature.

Anuran metamorphosis is one of the most spectacular processes in nature. Metamorphosis entails morphological transformations and extensive changes in feeding habits, such as transforming from an herbivore to a carnivore. This phenomenon is especially sensitive to environmental cues. We studied the phenotypic plasticity of intestinal morphology and enzyme activity in tadpoles of the Chilean giant frog Caudiverbera caudiverbera. We tested the effects of diet and temperature using a factorial design, which included a control of nontreated individuals. There was no significant effect of diet treatment (i.e., low- vs. high-quality diet) on any of the measured variables, including external morphology. We found significant effects of temperature on morphological traits. Temperature treatment also had significant effects on aminopeptidase-N and maltase activity. Both enzymes exhibited complex interactions with temperature along the intestine. Gut size varied significantly among temperatures, with intestines from warm-treated individuals smaller than the intestines from control and cold-treated tadpoles. Our findings suggest that phenotypic plasticity of intestinal morphology and physiology exists in larvae of this species, at least in response to temperature. However, we did not detect clear effects of diet or temperature on the timing of metamorphosis.

Animals↗

PubMed1992

Production of an extracellular polyethylene-degrading enzyme(s) by Streptomyces species.

Extracellular culture concentrates were prepared from Streptomyces viridosporus T7A, Streptomyces badius 252, and Streptomyces setonii 75Vi2 shake flask cultures. Ten-day-heat-treated (70 degrees C) starch-polyethylene degradable plastic films were incubated with shaking with active or inactive enzyme for 3 weeks (37 degrees C). Active enzyme illustrated changes in the films' Fourier transform infrared spectra, mechanical properties, and polyethylene molecular weight distributions.

Fourier Analysis↗

PubMed1998

Competence-specific induction of recA is required for full recombination proficiency during transformation in Streptococcus pneumoniae.

Transcriptional activation of the recA gene of Streptococcus pneumoniae was previously shown to occur at competence. A 5.7 kb recA-specific transcript that contained at least two additional genes, cinA and dinF, was identified. We now report the complete characterization of the recA operon and investigation of the role of the competence-specific induction of recA. The 5.7 kb competence-specific recA transcript is shown to include lytA, which encodes the pneumococcal autolysin, a protein previously shown to contribute to virulence of S. pneumoniae. Uncoupling (denoted Ind-) of recA and/or the downstream genes was achieved through the placement of transcription terminators within the operon, either upstream or downstream of recA. Prevention of the competence-specific induction of recA severely affected spontaneous transformation. Transformation efficiencies of recA+ (Ind-) and of wild-type cells were compared under various conditions and with different donor DNA. Chromosomal transformation was reduced 17-(chromosomal donor) to 45-fold (recombinant plasmid donor), depending on the donor DNA, and plasmid establishment was reduced 129-fold. Measurement of uptake of radioactively labelled donor DNA in transformed cells in parallel with scoring for transformants (chromosomal donor) revealed normal uptake, but a 21-fold reduction in recombination in a recA+ (Ind-) strain, indicating that the transformation defect was primarily in recombination. Strikingly enough, a much larger (460-fold) reduction in recombination was observed for the shortest homologous donor fragment used (878 nucleotides long). Possible interpretations of the observation that basal RecA appears unable to promote efficient recombination whatever the number and the length of donor fragments taken up are proposed. The role of recA induction is discussed in view of the potential contribution of transformation to genome plasticity in this pathogen.

Amidohydrolases↗

PubMed1988

Alterations of the biological characteristics of a colon carcinoma cell line by colon-derived substrata material.

This study documents the ability of substrata material derived from well but not poorly differentiated colon carcinoma cells to alter the biological characteristics of a separate colon carcinoma cell line (MOSERSF). To assess changes induced by the presence of these substrata, MOSERSF cells were screened for (a) morphological features, (b) secretion of carcinoembryonic antigen (CEA), (c) alteration of urokinase levels, and (d) sensitivity to the growth-inhibitory peptide transforming growth factor beta. Morphologically, MOSERSF cells grown on plastic displayed a rounded shape and could be detached by agitation. Subculturing of these cells onto substrata laid down by well differentiated (mature) colon carcinoma cells resulted in cell attachment and spreading. These changes did not manifest themselves when cells were plated on material derived from poorly differentiated (primitive) colon cells. Conditioned medium from MOSERSF cells grown on plastic or on colon-derived material from the well and poorly differentiated colon cells were compared for CEA levels. Substrata derived from undifferentiated cells were without effect on assayable CEA (substrata absent, 1.4 ng/ml/10(6) cells/72 h; substrata present, 1.4-1.7 ng/ml/10(6) cells/72 h). However, growth of MOSERSF cells on material deposited by well differentiated colon cells resulted in a 3-fold increase in the level of CEA. Spent medium was also analyzed for urokinase. A high level of the protease (20.3 ng/ml/10(6) cells/72 h) was expressed by MOSERSF cells. The concentration of the enzyme was reduced by over 50% when MOSERSF cells were propagated on substrata laid down by well differentiated cells. An enhanced sensitivity to the growth-retarding effects of transforming growth factor beta was seen with certain substrata. On plastic, transforming growth factor beta inhibited proliferation of MOSERSF cells with a median effective concentration of 0.65 ng/ml. However, on substrata from mature but not primitive cells, MOSERSF cells exhibited an increased sensitivity to the peptide (median effective concentration, 0.16 ng/ml). Colon-derived material obtained from both well differentiated and poorly differentiated colon carcinoma cells was compared after [35S]-methionine metabolic labeling. More [35S]methionine was incorporated into the material from the "mature" colon cells. The substrata could also be distinguished by quantitative differences in a number of high molecular weight proteins. Immunofluorescence of colon-deposited material revealed the presence of laminin and fibronectin.

Carcinoembryonic Antigen↗

PubMed1989

Isolation and characterization of a human monoclonal antibody that recognizes epitopes shared by Pseudomonas aeruginosa immunotype 1, 3, 4, and 6 lipopolysaccharides.

A hybridoma line secreting a human monoclonal antibody (HMAb) capable of recognizing Fisher immunotype (IT) 1, 3, 4, and 6 lipopolysaccharide (LPS) in vitro was isolated. Peripheral blood lymphocytes (PBL) were obtained from volunteers immunized with an experimental Pseudomonas aeruginosa O polysaccharide-toxin A vaccine. PBL-expressing surface antibodies able to bind to P. aeruginosa LPS were isolated by adsorption onto LPS-coated plastic wells. Such PBL were transformed with Epstein-Barr virus. Lymphoblastoid cell lines secreting anti-P. aeruginosa LPS antibodies were identified by an enzyme-linked immunosorbent assay and fused to the F3B6 heteromyeloma line. A hybridoma line producing a HMAb (2-8AH79) able to bind IT-1, IT-3, IT-4, and IT-6 LPS was identified by an enzyme-linked immunosorbent assay. This HMAb was found to bind to the O-polysaccharide regions of IT-1, IT-3, IT-4, and IT-6 LPS, as determined by immunoblotting. By using an immunofluorescence microscopy assay, the cell surfaces of IT-3 and IT-4 bacteria were strongly stained by HMAb 2-8AH79, whereas those of IT-1 and IT-6 bacteria were weakly stained. This HMAb was found to promote the uptake and killing of IT-3 and IT-4 bacteria, but not IT-1 or IT-6 organisms, by human polymorphonuclear leukocytes. Similarly, the passive transfer of HMAb 2-8AH79 to mice afforded significant protection only against a challenge with IT-3 and IT-4 bacteria.

Animals↗

PubMed1979

Oncogenic transformation of rat lung epitheloid cells by SV 40 DNA and restriction enzyme fragments.

Rat epitheloid lung cells were transformed with various preparations of SV40 dna using the Ca2+-precipitation technique. The amount of SV40 genetic information integrated into transformed clones was evaluated by DNA-DNA renaturation kinetics. The growth properties on plastic and in soft-agar were examined, as well as the ability to induce tumors in syngeneic new-born animals or in adult nude mice. One particular transformed line, which had received the Hpa II/BamH I A (59 per cent) fragment, was found to contain about 3 integrated copies of this fragment per cell and no significant amount of the Hpa II/BamH I B (41 per cent) fragment. This line which grew to high saturation densities and efficiently formed clones in low serum on plastic, produced tumors in both syngeneic rats and nude mice. Thus the Hpa II/BamH I A fragment, which mainly includes early viral information, was sufficient to impart these properties to rat epitheloid lung cells.

Animals↗

PubMed2004

Effect of short-chain fatty acids on the proliferation and differentiation of the human colonic adenocarcinoma cell line Caco-2.

OBJECTIVE: Short-chain fatty acids (SCFA) in the colon may maintain colonocyte differentiation and oppose carcinogenesis. The purpose of this study was to investigate the effects of three SCFA, butyrate, propionate and acetate, on the differentiation, proliferation, and matrix interactions of the Caco-2 human colonic adenocarcinoma cell line. METHODS: Differentiation was assessed by brush border enzyme expression and the doubling time (proliferation) was calculated directly from serial cell counts and by the logarithmic transformation method. Cell motility (migration) was quantitated by the expansion of a confluent Caco-2 monolayer (after release from a constraining fence) across bacteriologic plastic dishes precoated with saturating concentrations of type I collagen. Results were expressed as mean +/- SE and were analyzed by ANOVA and Bonferroni's modified t-test. RESULTS: All three SCFA studied altered the Caco-2 phenotype. Treatment with 10 mmol SCFA significantly prolonged the cell doubling time, promoted brush border enzyme expression (cathepsin C), and inhibited the motility of the Caco-2 cells. CONCLUSIONS: Butyrate, propionate and acetate inhibited the proliferation and motility of a well-differentiated human colonic cancer cell line while promoting the expression of the differentiation marker, cathepsin C. Thus the SCFA produced by bacterial fermentation of dietary fiber may exert a protective effect against the development of colon cancer.

Acetic Acid↗

PubMed2002

A role for protein kinase C and its substrates in the action of valproic acid in the brain: implications for neural plasticity.

Valproic acid (VPA) is a broad-spectrum anticonvulsant with well-documented teratogenic effects, but whose mechanism of action is largely unknown. In the present study we have examined the effects of VPA on the expression of two prominent substrates for protein kinase C (PKC) in the brain, MARCKS and GAP-43, which have been implicated in actin-membrane plasticity and neurite outgrowth during neuronal differentiation, respectively, and are essential to normal brain development. Immortalized hippocampal HN33 cells exposed to VPA exhibited reduced MARCKS protein expression and demonstrated increased GAP-43 protein expression, with concomitant alterations in cellular morphology, including an increase in the number and length of neurites and accompanied by a reduction in cell growth rate. The effects of VPA were observed at clinically relevant concentrations following chronic (>1 day) VPA exposure. We also present evidence for a VPA-induced alteration in PKC activity, as well as temporal changes in individual PKC isozyme expression. Inhibition of PKC with the PKC-selective inhibitor, LY333531, prevented the VPA-induced down-regulation of membrane-associated MARCKS, but had no effect on the cytosolic MARCKS reduction or the GAP-43 up-regulation. Inhibition of PKC by LY333531 enhanced the differentiating effects of VPA; additionally, LY333531 alone induced greater neurite outgrowth in this cell line. Collectively, these data indicate that VPA induces neuronal differentiation, associated with a reduction in MARCKS expression and an increase in GAP-43 expression, consistent with the hypothesis that a reduction in MARCKS at the membrane may be permissive for cytoskeletal plasticity during neurite outgrowth.

Animals↗

PubMed2025

Logan: Planetary-Scale Genome Assembly Surveys Life's Diversity.

The breadth of life's diversity is unfathomable, but public nucleic acid sequencing data offers a window into the dispersion and evolution of genetic diversity across Earth. However the rapid growth and accumulation of sequence data have outpaced efficient analysis capabilities. The largest collection of freely available sequencing data is the Sequence Read Archive (SRA), comprising 27.3 million datasets or 5 × 1016 basepairs. To realize the potential of the SRA, we constructed Logan, a massive sequence assembly transforming short reads into long contigs and compressing the data over 100-fold, enabling highly efficient petabase-scale analysis. We created Logan-Search, a k-mer index of Logan for free planetary-scale sequence search, returning matches in minutes. We used Logan contigs to identify >200 million plastic-degrading enzyme homologs, and validate novel enzymes with catalytic activities exceeding current reference standards. Further, we vastly expand the known diversity of proteins (30-fold over UniRef50), plasmids (22-fold over PLSDB), P4 satellites (4.5-fold), and the recently described Obelisk RNA elements (3.7-fold). Logan also enables ecological and biomedical data mining, such as global tracking of antimicrobial resistance genes and the characterization of viral reactivation across millions of human BioSamples. By transforming the SRA, Logan democratizes access to the world's public genetic data and opens frontiers in biotechnology, molecular ecology, and global health.

Journal Article↗

PubMedDate not supplied

[NO-Ergic transmission and NO as a volume transmitter. Effect of NO on mechanisms of synaptic plasticity and epileptogenesis].

Nitric oxide (NO) is a universal intercellular messenger and the only molecule known so far, which satisfies all requirements of the volume (extrasynaptic) neurotransmitter. The effect of NO on target cells is so read in the four-dimensional coordinate system by combining both the spatial and the temporal components of the nervous activity. In this review, the authors, based on literature data and own studies, present a detailed analysis of properties of NO as a volume neurotransmitter at formation of phenomena of synaptic plasticity in norm and pathology. An evaluation is given of cytotoxic and neuroprotective effects of NO under conditions of the brain tissue ischemia and phenomena of hyperexcitability in foci of epileptiform activity. It is emphasized that the long-term potentiation and long-term depression, phenomena of physiological plasticity, can be transformed into pathological plasticity at disturbances of equilibrium between neuroprotective and neurotoxic effects of NO.

Animals↗

PubMed2006

Differences in protonation of ubiquinone and menaquinone in fumarate reductase from Escherichia coli.

Escherichia coli quinol-fumarate reductase operates with both natural quinones, ubiquinone (UQ) and menaquinone (MQ), at a single quinone binding site. We have utilized a combination of mutagenesis, kinetic, EPR, and Fourier transform infrared methods to study the role of two residues, Lys-B228 and Glu-C29, at the quinol-fumarate reductase quinone binding site in reactions with MQ and UQ. The data demonstrate that Lys-B228 provides a strong hydrogen bond to MQ and is essential for reactions with both quinone types. Substitution of Glu-C29 with Leu and Phe caused a dramatic decrease in enzymatic reactions with MQ in agreement with previous studies, however, the succinate-UQ reductase reaction remains unaffected. Elimination of a negative charge in Glu-C29 mutant enzymes resulted in significantly increased stabilization of both UQ-* and MQ-* semiquinones. The data presented here suggest similar hydrogen bonding of the C1 carbonyl of both MQ and UQ, whereas there is different hydrogen bonding for their C4 carbonyls. The differences are shown by a single point mutation of Glu-C29, which transforms the enzyme from one that is predominantly a menaquinol-fumarate reductase to one that is essentially only functional as a succinate-ubiquinone reductase. These findings represent an example of how enzymes that are designed to accommodate either UQ or MQ at a single Q binding site may nevertheless develop sufficient plasticity at the binding pocket to react differently with MQ and UQ.

Binding Sites↗

PubMed1977

[Bacterial recombination].

The most perspective trends in studying the mechanisms of genetic exchanges in bacteria are discussed. They are the following. 1. Comparison of the recombination stages in various biological phenomena such as transformation, transduction (generalized), conjugation (common and single-stranded) and transfection. 2. Characterization of genetic determinants and basic enzymes of the recombination process in Rec-systems of different bacteria. 3. Determination of some peculiar features of the intragenic recombination and finding a possible approach to their research. 4. Analysis of some plastic properties of the DNA structure and their application to the modern ideas in the formulation of a molecular mechanism of genetic recombination.

Bacillus subtilis↗