@article {2461, title = {Direct Measurement of the Kinetics of CBM9 Fusion-Tag Bioprocessing Using Luminescence Resonance Energy Transfer}, journal = {Biotechnology Progress}, volume = {25}, number = {3}, year = {2009}, note = {ISI Document Delivery No.: 462SETimes Cited: 1Cited Reference Count: 44Kavoosi, Mojgan Creagh, A. Louise Turner, Robin F. B. Kilburn, Douglas G. Haynes, Charles A.}, month = {May-Jun}, pages = {874-881}, type = {Article}, abstract = {The economics of affinity-tagging technologies, particularly at preparative scales, depends in part on the cost and efficiency of the bioprocessing step used to remove the affinity tag and obtain the final purified product (Lowe et al., J Biochem Biophys Methods. 2001,49:561-574). When CBM9, the family 9 cellulose binding module from Thermotoga maritima, serves as the affinity tag, the overall efficiency of tag removal is a function of the choice of processing enzyme and the local structure of the cleavage site, most notably the linker sequence flanking the bioprocessing recognition site on the tag side. A novel spectroscopic method is reported and used to rapidly and accurately measure CBM9 fusion-tag bioprocessing kinetics and their dependence on the choice of linker sequence. The assay monitors energy transfer between a lanthanide-based donor bound to the CBM9 tag and an acceptor fluorophore presented on the tat-get protein or peptide. Enzyme-catalyzed cleavage of the fusion tag terminates this resonance energy transfer, resulting in a change in fluorescence intensity that can be monitored to quantify substrate concentration over time. The assay is simple, fast and accurate, providing k(cat)/K-M values that contain standard errors of less than 3\%. As a result, both substantial and subtle differences in bioprocessing kinetics can be measured and used to guide bioproduct design. (C) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 25: 874-881, 2009}, keywords = {10A, ACTIVE-SITE, affinity chromatography, BEND ANGLE, CARBOHYDRATE-BINDING MODULE, CONFORMATIONAL-CHANGES, enterokinase, ESCHERICHIA-COLI, fusion tag, green fluorescent protein (GFP), high throughput assay, LANTHANIDE, library, linker, luminescence, protein purification, PURIFICATION, RECOMBINANT PROTEINS, resonance energy transfer (LRET), RNA-POLYMERASE, terbium, THERMOTOGA-MARITIMA, XYLANASE}, isbn = {8756-7938}, url = {://000267375500030}, author = {Kavoosi, M. and Creagh, A. L. and Turner, R. F. B. and Kilburn, D. G. and Haynes, C. A.} } @article {2290, title = {Mass spectrometric identification of formaldehyde-induced peptide modifications under in vivo protein cross-linking conditions}, journal = {Analytica Chimica Acta}, volume = {618}, number = {2}, year = {2008}, note = {ISI Document Delivery No.: 317FDTimes Cited: 10Cited Reference Count: 19Toews, Judy Rogalski, Jason C. Clark, Thomas J. Kast, Juergen}, month = {Jun}, pages = {168-183}, type = {Article}, abstract = {Formaldehyde cross-linking of proteins is emerging as a novel approach to study protein-protein interactions in living cells. It has been shown to be compatible with standard techniques used in functional proteomics such as affinity-based protein enrichment, enzymatic digestion, and mass spectrometric protein identification. So far, the lack of knowledge on formaldehyde-induced protein modifications and suitable mass spectrometric methods for their targeted detection has impeded the identification of the different types of crosslinked peptides in these samples. In particular, it has remained unclear whether in vitro studies that identified a multitude of amino acid residues reacting with formaldehyde over the course of several days are suitable substitutes for the much shorter reaction times of 10-20 min used in cross-linking experiments in living cells. The current study on model peptides identifies amino-termini as well as lysine, tryptophan, and cysteine side chains, i.e. a small subset of those modified after several days, as the major reactive sites under such conditions, and suggests relative position in the peptide sequence as well as sequence microenvironment to be important factors that govern reactivity. Using MALDI-MS, mass increases of 12 Da on amino groups and 30 Da on cysteines were detected as the major reaction products, while peptide fragment ion analysis by tandem mass spectrometry was used to localize the actual modification sites on a peptide. Non-specific cross-linking was absent, and could only be detected with low yield at elevated peptide concentrations. The detailed knowledge on the constraints and products of the formaldehyde reaction with peptides after short incubation times presented in this study is expected to facilitate the targeted mass spectrometric analysis of proteins after in vivo formaldehyde cross-linking. (c) 2008 Elsevier B.V. All rights reserved.}, keywords = {Chemical modification, COMPLEXES, FORMALDEHYDE, MAP, mass, NETWORK, peptide fragmentation, protein cross-linking, PROTEOMICS, PURIFICATION, REACTIVITY, SPECTROMETRY}, isbn = {0003-2670}, url = {://000257004400006}, author = {Toews, J. and Rogalski, J. C. and Clark, T. J. and Kast, J.} } @article {950, title = {Identification and mechanism of a bacterial hydrolyzing UDP-N-acetylglucosamine 2-epimerase}, journal = {Biochemistry}, volume = {43}, number = {44}, year = {2004}, note = {ISI Document Delivery No.: 868UVTimes Cited: 13Cited Reference Count: 38}, month = {Nov}, pages = {14290-14298}, type = {Article}, abstract = {This paper reports the first identification of a fully functional hydrolyzing UDP-N-acetylglucosamine 2-epimerase from a bacterial source. The epimerase (known as SiaA or NeuC from Neisseria meningitidis MC58 group B is shown to catalyze the conversion of UDP-GlcNAc into ManNAc and UDP in the first step of sialic acid (N-acetylneuraminic acid) biosynthesis. The mechanism is proposed to involve an anti elimination of UDP to form 2-acetamidoglucal as an intermediate, followed by the syn addition of water. The observation that the alpha-anomer of ManNAc is the true product and that solvent deuterium is incorporated at C-2 is consistent with this mechanism. The use of the O-18-labeled substrate confirms that the overall hydrolysis reaction proceeds via cleavage of the C-O bond. Furthermore, the putative intermediate 2-acetamidoglucal is shown to serve as a catalytically competent substrate and is enzymatically hydrated to give ManNAc exclusively. Isotope effect studies show that cleavage of the C-H bond is not rate limiting during catalysis. Mutagenesis studies show that three active site carboxylate residues are crucial for catalysis. In two of the mutants that were studied (E122Q and D131N), 2-acetamidoglucal was released from the active site during catalysis, providing direct evidence that the enzyme is capable of catalyzing the anti elimination of UDP from UDP-GlcNAc.}, keywords = {2-EPIMERASE/N-ACETYLMANNOSAMINE, biosynthesis, CELL-INTERACTIONS, ENZYME, ESCHERICHIA-COLI K1, KINASE, POLYSIALIC ACID, PURIFICATION, RAT-LIVER, SIALIC-ACID, STEREOCHEMISTRY}, isbn = {0006-2960}, url = {://000224939400045}, author = {Murkin, A. S. and Chou, W. K. and Wakarchuk, W. W. and Tanner, M. E.} } @article {687, title = {A quantitative study of continuous flow-counterbalanced capillary electrophoresis for sample purification}, journal = {Electrophoresis}, volume = {24}, number = {17}, year = {2003}, note = {ISI Document Delivery No.: 723ZZTimes Cited: 10Cited Reference Count: 25}, month = {Sep}, pages = {2887-2895}, type = {Article}, abstract = {A systematic evaluation of continuous flow-counterbalanced capillary electrophoresis for microscale preparative applications is presented. The success of the technique was found to depend on the specific nature of the analyte and background electrolyte and was most heavily influenced by factors such as solution conductivity and rate of buffer depletion. The performance of the technique for the system studied was ultimately limited by contamination arising from changes in analyte mobilities during extended run times. Marked improvements in both purification rate and yield were observed using the zwitterionic buffer 2-(N-cyclohexylamino)ethanesulfonic acid when compared to similar runs carried out using a borate background electrolyte. A quantitative evaluation of the technique was performed for the analytes studied and the performance of the technique has been compared to fraction collection methods. The highest recovery achieved was 5.2\% of the fastest migrating component present in the original sample with a resolution of 9 to the adjacent peak and required 100 min under optimized conditions. Recovery could be further increased to 9.0\% in 120 min for the same analyte using pressure-ramped flow-counterbalanced capillary electrophoresis.}, keywords = {amino acid, BUFFER, DESIGN, flow-counterbalanced capillary electrophoresis, FRACTION COLLECTOR, LASER-INDUCED FLUORESCENCE, MASS-SPECTROMETRY, MEMBRANE, MICELLAR ELECTROKINETIC CHROMATOGRAPHY, PLASMA, PURIFICATION, SAMPLE, SEPARATION, tetramethylrhodamine isothiocyanate, ZONE-ELECTROPHORESIS, zwitterionic buffer}, isbn = {0173-0835}, url = {://000185462800002}, author = {McLaren, D. G. and Chen, D. D. Y.} } @article {629, title = {Toward binary nitrosyls: Distinctly bent Fe-N-O linkages in base-stabilized Fe(NO)(3)(+) complexes}, journal = {Journal of the American Chemical Society}, volume = {125}, number = {42}, year = {2003}, note = {ISI Document Delivery No.: 733FYTimes Cited: 15Cited Reference Count: 50}, month = {Oct}, pages = {12935-12944}, type = {Article}, abstract = {Air- and moisture-sensitive Fe(NO)(3)(eta(1)-PF6) (1) may be conveniently prepared by treating Fe(NO)(3)Cl with 1 equiv of [Ag][PF6] in CH2Cl2 or by reacting [NO][PF6] with excess iron filings in MeNO2. Complex 1 is thermally sensitive both as a solid and in solutions, and is best handled below -20 degreesC. To isolate 1 reproducibly from MeNO2 solutions it is necessary to remove all traces of propionitrile, which often occurs as an impurity in MeNO2, because it reacts with Lewis-acidic 1 to form [Fe(NO)(3)(EtCN)][PF6] (2). If trace H2O is present during the synthesis of 1, some of the PF6- is converted to PO2F2-, which is sufficiently Lewis basic that it captures two Fe(NO)(3)(+) fragments and forms [(ON)(3)Fe(mu-PO2F2)Fe(NO)(3)]-[PF6] (3). Finally, Fe(NO)(3)(eta(1)-BF4) (4) can be obtained as a green microcrystalline powder by employing the same synthetic methodologies used to prepare 1. The new complexes 1-4 have been characterized by conventional spectroscopic methods, and the solid-state molecular structures of 2, 3, and 4 and their parent compound, Fe(NO)(3)Cl, have been established by X-ray diffraction methods. The iron centers in the Fe(NO)(3) fragments in all these structures exhibit approximately tetrahedral coordination geometries, and the Fe-N-O linkages are distinctly nonlinear with bond angles in the range of 159 to 169degrees. DFT calculations on Fe(NO)(3)(eta(1)-BF4) (4) confirm that its bent Fe-N-O links have an electronic origin and need not be attributed to other factors, such as packing forces in the crystal. Interestingly, the bending of the NO ligands results in an increase in the energy of the HOMO, relative to the linear case, but at the same time causes a decrease in energy of the HOMO-1 and the HOMO-2 molecular orbitals. This more than compensates for the higher energy of the HOMO, resulting in a lower energy structure.}, keywords = {basis set, CALCULATIONS, COORDINATION, CRYSTAL-STRUCTURE, density, impurities, MOLECULAR, NITROMETHANE, PURIFICATION, REFINEMENT, TETRANITROSYLCHROMIUM CR(NO)4}, isbn = {0002-7863}, url = {://000185990300054}, author = {Hayton, T. W. and McNeil, W. S. and Patrick, B. O. and Legzdins,Peter} } @article {4557, title = {Catalytic acid/base residues of glutamate racemase}, journal = {Biochemistry}, volume = {38}, number = {13}, year = {1999}, note = {ISI Document Delivery No.: 182QZTimes Cited: 43Cited Reference Count: 37}, month = {Mar}, pages = {4106-4113}, type = {Article}, abstract = {Glutamate racemase is a cofactor-independent enzyme that employs two active-site cysteine residues as acid/base catalysts during the interconversion of glutamate enantiomers, In a given reaction direction, a thiolate from one of the cysteines abstracts the alpha-proton, and the other cysteine thiol delivers a proton to the opposite face of the resulting carbanionic intermediate. This paper reports that the C73S and C184S mutants are still capable of racemizing glutamate with specificity constants about 10(3)-fold lower than those of the wild-type enzyme, A "one-base requiring" reaction, the elimination of water from N-hydroxyglutamate, has been used to deduce which thiol acts as the base for a given enantiomer. With D-N-hydroxyglutamate the C73S mutant is a much poorer catalyst than wild-type enzyme, whereas the C184S mutant is a somewhat better catalyst. This trend was reversed with L-N-hydroxyglutamate, suggesting that Cys73 is responsible for the deprotonation of D-glutamate and Cys184 is responsible for the deprotonation of L-glutamate. In addition, with C73S the V-max/K-M isotope effect on D-glutamate racemization was greater than that seen with wild-type enzyme, whereas the isotope effect with L-glutamate had decreased. The results were reversed with the C184S mutant. This is interpreted as being due to an asymmetry in the free energy profiles that is induced upon mutation, with the deprotonation step involving a serine becoming the more cleanly rate-determining of the two. These results support the above assignment and the notion that a carbanionic intermediate is formed during catalysis.}, keywords = {BACILLUS-STEAROTHERMOPHILUS, DIAMINOPIMELATE EPIMERASE, ENERGETICS, ESCHERICHIA-COLI, INHIBITOR, IRREVERSIBLE, L-ALANINE, MANDELATE RACEMASE, MECHANISM, PROLINE RACEMASE, PURIFICATION}, isbn = {0006-2960}, url = {://000079510800031}, author = {Glavas, S. and Tanner, M. E.} } @article {4673, title = {Metabolism of arsenic in primary cultures of human and rat hepatocytes}, journal = {Chemical Research in Toxicology}, volume = {12}, number = {7}, year = {1999}, note = {ISI Document Delivery No.: 219JCTimes Cited: 81Cited Reference Count: 26}, month = {Jul}, pages = {560-565}, type = {Article}, abstract = {The liver is considered a major site for methylation of inorganic arsenic (iAs). However, there is Little data on the capacity of human liver to methylate iAs. This work examined the metabolism of arsenite (iAs(III)), arsenate (iAs(v)), methylarsine oxide ((MAsO)-O-III), methylarsonic acid (MAsv), dimethylarsinous acid (DMAsIII), and dimethylarsinic acid (DMAsV) in primary cultures of normal human hepatocytes. Primary rat hepatocytes were used as methylating controls, iAs(III) and (MAsO)-O-III were metabolized more extensively than iAs(v) and MAsv by either cell type. Neither human nor rat hepatocytes metabolized DMAsIII or DMAsV. Methylation of iAs(III) by human hepatocytes yielded methylarsenic (MAs) and dimethylarsenic (DMAs) species; (MAsO)-O-III was converted to DMAs. The total methylation yield (MAs and DMAs) increased over the range of 0.1 to 4 mu M iAs(III). However, DMAs production was inhibited by iAs(III) in a concentration-dependent manner, and the DMAs/MAs ratio decreased. iAs(III) (10 and 20 mu M) inhibited both methylation reactions. Inhibition of DMAs synthesis resulted in accumulation of iAs and MAs in human hepatocytes, suggesting that dimethylation is required for iAs clearance from cells. Methylation capacities of human hepatocytes obtained from four donors ranged from 3.1 to 35.7 pmol of iAs(III) per 10(6) cells per hour and were substantially lower than the methylation capacity of rat hepatocytes (387 pmol of iAs(III) per 10(6) cells per hour). The maximal methylation rates for either rat or human hepatocytes were attained between 0.4 and 4 mu M iAs(III). In summary, (i) human hepatocytes methylate iAs, (ii) the capacities for iAs methylation vary among individuals and are saturable, and (iii) moderate concentrations of iAs inhibit DMAs synthesis, resulting in an accumulation of iAs and MAs in cells.}, keywords = {ASSAY, ENZYMATIC METHYLATION, IN-VITRO, INGESTION, LIVER, PURIFICATION, TOXICITY, URINARY-EXCRETION}, isbn = {0893-228X}, url = {://000081603300003}, author = {Styblo, M. and Del Razo, L. M. and LeCluyse, E. L. and Hamilton, G. A. and Wang, C. Q. and Cullen, W. R. and Thomas, D. J.} } @article {4647, title = {The structures of the neurotrophin 4 homodimer and the brain-derived neurotrophic factor/neurotrophin 4 heterodimer reveal a common Trk-binding site}, journal = {Protein Science}, volume = {8}, number = {12}, year = {1999}, note = {ISI Document Delivery No.: 266RPTimes Cited: 24Cited Reference Count: 45}, month = {Dec}, pages = {2589-2597}, type = {Article}, abstract = {The neurotrophins are growth factors that are involved in the development and survival of neurons. Neurotrophin release by a target tissue results in neuron growth along the neurotrophin concentration gradient, culminating in the eventual innervation of the target tissue. These activities are mediated through trk cell surface receptors. We have determined the structures of the heterodimer formed between brain-derived neurotrophic factor (BDNF) and neurotrophin 4 (NT4), as well as the structure of homodimer of NT4. We also present the structure of the Neurotrophin 3 homodimer, which is refined to higher resolution than previously published. These structures provide the first views of the architecture of the NT4 protomer. Comparison of the surface of a model of the BDNF homodimer with the structures of the neurotrophin homodimers reveals common features that may be important in the binding between the neurotrophins and their receptors. In particular, there exists an analogous region on the surface of each neurotrophin that is likely to be involved in trk receptor binding. Variations in sequence on the periphery of this common region serve to confer trk receptor specificity.}, keywords = {BDNF, CELLS, CRYSTAL-STRUCTURE, CRYSTALLOGRAPHY, DIFFERENTIATION, nerve growth factor, NERVE GROWTH-FACTOR, NGF, PURIFICATION, RECEPTOR, RECEPTORS, RECOGNITION, SPECIFICITY}, isbn = {0961-8368}, url = {://000084314100005}, author = {Robinson, R. C. and Radziejewski, C. and Spraggon, G. and Greenwald, J. and Kostura, M. R. and Burtnick, L. D. and Stuart, D. I. and Choe, S. and Jones, E. Y.} } @article {4689, title = {Undercarboxylation of recombinant prothrombin revealed by analysis of gamma-carboxyglutamic acid using capillary electrophoresis and laser-induced fluorescence}, journal = {Febs Letters}, volume = {445}, number = {2-3}, year = {1999}, note = {ISI Document Delivery No.: 175YCTimes Cited: 6Cited Reference Count: 37}, month = {Feb}, pages = {256-260}, type = {Article}, abstract = {The gamma-carboxyglutamic acid (Gla) content of several variants of human prothrombin has been measured by using capillary electrophoresis and laser-induced fluorescence (CE-LIF). Both plasma-derived prothrombin and recombinant prothrombin contain ten residues of Gla per molecule of protein. In contrast, a variant of human prothrombin (containing the second kringle domain of bovine prothrombin) was separated into two populations that differed in their Gla content. Direct measurement of the Gla content showed an association with the presence or absence of the calcium-dependent conformational change that is required for prothombinase function. Thus, the CE-LIF assay is useful in determining the carboxylation status of recombinant proteins. (C) 1999 Federation of European Biochemical Societies.}, keywords = {baby hamster kidney, calcium, capillary electrophoresis, cell, EXPRESSION, FACTOR-X, gamma carboxy glutamic acid, GLUTAMIC-ACID, HUMAN PROTEIN-C, LASER-INDUCED FLUORESCENCE, METAL, PHOSPHOLIPID-BINDING-PROPERTIES, PROTHROMBIN, PURIFICATION, recombinant protein, RESIDUES, VITAMIN-K}, isbn = {0014-5793}, url = {://000079122800007}, author = {Vo, H. C. and Britz-McKibbin, P. and Chen, D. D. Y. and MacGillivray, R. T. A.} } @article {4298, title = {Epimerization via carbon-carbon bond cleavage. L-ribulose-5-phosphate 4-epimerase as a masked class II aldolase}, journal = {Biochemistry}, volume = {37}, number = {16}, year = {1998}, note = {ISI Document Delivery No.: ZM208Times Cited: 32Cited Reference Count: 35}, month = {Apr}, pages = {5746-5754}, type = {Article}, abstract = {Studies indicating that the E. coli L-ribulose-5-phosphate 4-epimerase employs an "aldolase-like" mechanism are reported. This NAD(+)-independent enzyme epimerizes a steseocenter that does not bear an acidic proton and therefore it cannot utilize a simple deprotonation-reprotonation mechanism. Sequence similarities between the epimerase and the class II L-fuculose-1-phosphate aldolase suggest that the two may be evolutionarily related and that the epimerization may occur via carbon-carbon bond cleavage and re-formation. Conserved residues thought to provide the metal ion ligands of the epimerase have been modified using site-directed mutagenesis. The resulting mutants show low k(cat) values in addition to a reduced affinity for Zn2+. These observations serve to establish that there is a structural link between between the active site geometry of the epimerase and the aldolase. In addition, the H97N mutant was found to catalyze the condensation of dihydroxyacetone and glycolaldehyde phosphate to produce a mixture of L-ribulose-5-phosphate and D-xylulose-5-phosphate. This observation of aldolase activity establishes that the epimerase active site is capable of promoting carbon-carbon bond cleavage. Furthermore, glycolaldehyde phosphate was shown to be a competitive inhibitor of the mutant enzyme (K-t = 0.37 mM) but not of the wild-type enzyme. The mutation apparently causes the epimerase to become "leaky" and enables it to bind/generate the normal reaction intermediates from the unbound aldol cleavage products.}, keywords = {ENZYMES, ESCHERICHIA-COLI, L-FUCULOSE-1-PHOSPHATE ALDOLASE, MECHANISM, MUTAGENESIS, ORGANIC-SYNTHESIS, PCR, PURIFICATION, SEQUENCE, SITE}, isbn = {0006-2960}, url = {://000073515500048}, author = {Johnson, A. E. and Tanner, M. E.} } @article {3763, title = {Driving forces for DNA adsorption to silica in perchlorate solutions}, journal = {Journal of Colloid and Interface Science}, volume = {181}, number = {2}, year = {1996}, note = {ISI Document Delivery No.: UZ536Times Cited: 112Cited Reference Count: 43}, month = {Aug}, pages = {635-644}, type = {Article}, abstract = {The adsorption of both plasmid and chromosomal duplex DNA to silica is investigated with the aim of determining the dominant forces involved in the binding reaction. Changes in the initial slopes and plateau values of adsorption isotherms for DNA on microcrystalline silica particles are used to establish the sensitivity of the binding reaction to ionic strength, temperature and pH, and DNA size and conformation. Binding is driven by an increase in entropy, with little or no enthalpic contribution. Adsorption isotherm results indicate that three effects, namely: (i) shielded intermolecular electrostatic forces, (ii) dehydration of the DNA and silica surfaces, and (iii) intermolecular hydrogen bond formation in the DNA-silica contact layer, make the dominant contributions to the overall driving force for adsorption. (C) 1996 Academic Press, Inc.}, keywords = {adsorption isotherms, ARRAYS, CHIPS, CONFORMATION, DNA, DNA adsorption, DNA binding, DNA PURIFICATION, DNA-silica interactions, ELECTROPHORESIS, GLOBULAR-PROTEINS, PLASMID DNA, PURIFICATION, SURFACES, TRANSITION}, isbn = {0021-9797}, url = {://A1996UZ53600031}, author = {Melzak, K. A. and Sherwood, C. S. and Turner, R. F. B. and Haynes, C. A.} } @article {3832, title = {Phosphinate inhibitors of the D-glutamic acid-adding enzyme of peptidoglycan biosynthesis}, journal = {Journal of Organic Chemistry}, volume = {61}, number = {5}, year = {1996}, note = {ISI Document Delivery No.: TZ997Times Cited: 66Cited Reference Count: 31}, month = {Mar}, pages = {1756-1760}, type = {Article}, abstract = {We report the synthesis and initial evaluation of the first effective inhibitors of the D-glutamic acid-adding enzyme (UDP-N-acetylmuramoyl-L-alanine:D-glutamate ligase or MurD). This enzyme plays a key role in bacterial peptidoglycan biosynthesis and is therefore a target for antibiotic design. Phosphinic acid 3 is a dipeptide analog linked to uridine diphosphate by a hydrophobic spacer. It is a good inhibitor of the enzyme (IC50 = 0.68 mu M) as it closely resembles the tetrahedral intermediate that is presumed to form in the ligation reaction. Compound 4 lacks the terminal UMP group, and compound 5 lacks both the linker and UDP functionalities. These are less effective inhibitors of the enzyme with IC50 values of 29 mu M and > 1 mM, respectively. Preincubation of the enzyme in the presence of inhibitor 3 and ATP does not result in irreversible inhibition or in the formation of a slowly decomplexing species, suggesting that the phosphinic acid is not phosphorylated in the active site.}, keywords = {(AMINOALKYL)PHOSPHINATE, ATP, D-ALANINE LIGASE, ESCHERICHIA-COLI, INACTIVATION, MECHANISM, PHOSPHINOTHRICIN, PURIFICATION, RAPID-QUENCH, SYNTHETASE}, isbn = {0022-3263}, url = {://A1996TZ99700030}, author = {Tanner, M. E. and Vaganay, S. and vanHeijenoort, J. and Blanot, D.} } @article {3288, title = {METALLOPHTHALOCYANINES AS POSSIBLE LIGNIN PEROXIDASE MODELS}, journal = {Bioorganic \& Medicinal Chemistry}, volume = {3}, number = {5}, year = {1995}, note = {ISI Document Delivery No.: RA974Times Cited: 5Cited Reference Count: 31}, month = {May}, pages = {471-477}, type = {Article}, abstract = {Several metalloporphyrins, particularly highly chlorinated water soluble meso-tetraphenylporphyrins, have been to be good biomimetics of the lignin peroxidases which degrade lignin in vivo. Metal complexes of the water soluble phthalocyaninetetrasulfonic acid have been examined as catalysts for the oxidation of lignin since the phthalocyanines are readily available and inexpensive. The copper(II), nickel(II) and cobalt(II) complexes showed little catalytic activity towards the oxidation of veratryl alcohol (a substrate of the lignin peroxidases). The iron(III) and manganese(III) complexes on the other hand were able to catalyze the oxidation of veratryl alcohol, 4-ethoxy-3-methoxyphenyl-glycerol-beta-guaiacyl ether (a beta-O-4-dimer) and 1-(4-ethoxy-3-methoxy)-2-(4-methoxyphenyl)-1,3-propanediol (a beta-1 dimer). These catalysts are, however, much less stable than the halogenated meso-tetraphenylporphyrins and this lower stability, which is dependent upon pH and the oxidant, limits their use as catalysts.}, keywords = {BASIDIOMYCETE, CATALYSIS, DEGRADING ENZYME, EPOXIDATION, OXYGEN, PHANEROCHAETE-CHRYSOSPORIUM, PURIFICATION}, isbn = {0968-0896}, url = {://A1995RA97400001}, author = {Cui, F. T. and Dolphin, D.} } @article {3106, title = {CLONING, SEQUENCING, AND VISCOMETRIC ADHESION ANALYSIS OF HEAT-RESISTANT AGGLUTININ 1, AN INTEGRAL MEMBRANE HEMAGGLUTININ FROM ESCHERICHIA-COLI-O9-H10-K99}, journal = {Infection and Immunity}, volume = {62}, number = {11}, year = {1994}, note = {ISI Document Delivery No.: PN304Times Cited: 13Cited Reference Count: 45}, month = {Nov}, pages = {5020-5026}, type = {Article}, abstract = {The gene encoding a mannose-resistant hemagglutinating protein was cloned from Escherichia coli 09:H10:K99. The hemagglutinin is different from two other mannose-resistant hemagglutinins in this strain, K99 and F41. The agglutinin, named heat-resistant agglutinin 1 (HRA1) since heating to 70 degrees C does not destroy its aggregative properties, strongly agglutinates human, pig, and dog erythrocytes, shows little or no affinity towards cow and chicken erythrocytes, but agglutinates human colon adenocarcinoma 201 (COLO 201) cells. The hra1 gene present on the recombinant plasmid pETE1 was localized by subcloning, and its nucleotide sequence was determined. The gene consists of a 792-bp open reading frame coding for a putative protein of 29 kDa with a predicted N-terminal secretory signal sequence. HRA1 shares no significant identity with data base protein sequences. HRA1 is strongly associated with the bacterial membrane, resisting sonication and isolation attempts based upon standard adhesin purification techniques. N-terminal sequencing of a unique 25-kDa band present in polyacrylamide gels of outer membrane preparations of bacteria harboring pETE1 correlated with the predicted N-terminal amino acid sequence of HRA1 after cleavage of the signal peptide. A viscometric agglutination assay sensitive to the strength of bacterial adhesion shows that the agglutination mediated by bacteria expressing HRA1 is weaker than that of bacteria bearing the F41 adhesin, probably because of the high-molecular-weight, multivalent nature of the latter adhesin. Our observations suggest that HRA1 is a monomeric outer membrane agglutinin.}, keywords = {ANTIGEN, BACTERIA, DNA, K99, LOCALIZATION, NONFIMBRIAL, OUTER-MEMBRANE, PROTEINS, PURIFICATION, STRAINS}, isbn = {0019-9567}, url = {://A1994PN30400046}, author = {Lutwyche, P. and Rupps, R. and Cavanagh, J. and Warren, R. A. J. and Brooks, D. E.} } @article {7360, title = {HYDROXYPROPYL CELLULOSE POLY(ETHYLENE GLYCOL)-CO-POLY(PROPYLENE GLYCOL) AQUEOUS 2-PHASE SYSTEMS - SYSTEM CHARACTERIZATION AND PARTITION OF CELLS AND PROTEINS}, journal = {Enzyme and Microbial Technology}, volume = {14}, number = {10}, year = {1992}, note = {ISI Document Delivery No.: JP468Times Cited: 16Cited Reference Count: 23}, month = {Oct}, pages = {785-790}, type = {Article}, abstract = {Novel aqueous polymeric two-phase systems are described. These systems are formed by mixing hydroxypropyl cellulose (molecular mass 100,000, trade name Klucel L) with poly(ethylene glycol)-co-poly(propylene glycol) copolymer [molecular mass 6,500, poly(propylene glycol) content 50\% w/w, trade name Pluronic P105], in a saline buffer. The phase diagram was measured and the interfacial tensions, phase separation times, and lower phase viscosities of three phase systems having constant Pluronic P105 concentration but varying in Klucel L concentration were determined. The partition behavior of a representative cell, bacterium, and protein and the affinity ligand-mediated alteration in the partition behavior of a protein from a yeast extract protein mixture were also characterized. The results suggest that Klucel L/Pluronic P105 phase systems may be cost-effective substitutes for, or complements to, existing aqueous polymeric phase systems. The physical characterization and representative partition data reported here should facilitate application of these new systems.}, keywords = {AFFINITY, AQUEOUS 2-PHASE SYSTEMS, BAKERS-YEAST, DEXTRAN, GLUCOSE-6-PHOSPHATE DEHYDROGENASE, GLYCOL)-CO-POLY(PROPYLENE GLYCOL) COPOLYMER, HUMAN ERYTHROCYTE, HYDROXYPROPYL CELLULOSE, PARTITION, POLY(ETHYLENE, polymer, PURIFICATION, SALMONELLA-ENTERIDITIS, TENSION}, isbn = {0141-0229}, url = {://A1992JP46800002}, author = {Skuse, D. R. and Norrisjones, R. and Yalpani, M. and Brooks, D. E.} }