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Liu CZ, Zhu RQ, Zhou ZJ, Ye ZG, Guo HC, Zuo LE. [Extracorporeal membrane oxygenation therapy for catecholamine-induced cardiomyopathy complicating circulatory shock in a female patient with paraganglioma]. Zhonghua Xin Xue Guan Bing Za Zhi 2019; 47:742-744. [PMID: 31550847 DOI: 10.3760/cma.j.issn.0253-3758.2019.09.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- C Z Liu
- Department of Critical Care Medicine, Shunde Hospital, Southern Medical University, Foshan 528300, China
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Liu JX, He N, Liu CY, Wang GR, Xin Q, Guo HC. Engineering the porosity and acidity of H-Beta zeolite by dealumination for the production of 2-ethylanthraquinone via 2-(4′-ethylbenzoyl)benzoic acid dehydration. RSC Adv 2018; 8:9731-9740. [PMID: 35540810 PMCID: PMC9078711 DOI: 10.1039/c7ra13576a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/19/2018] [Indexed: 11/21/2022] Open
Abstract
Environmentally-friendly zeolites have been used commercially to replace concentrated sulfuric acid and oleum in the alkylation reactions and dehydration of alcohols. However, moderate activity, associated with access and diffusion limitations, low intramolecular dehydration selectivity, associated with unsatisfactory acidity, and unknown reusability have hampered their industrial implementation in the dehydration of bulky 2-(4′-ethylbenzoyl)benzoic acid (E-BBA) to 2-ethylanthraquinone (2-EAQ). Herein, we have discovered that after being treated with mild HNO3, nano-sized H-Beta zeolite showed outstanding catalytic activity, selectivity and reusability, compared with a commercial oleum catalyst. A number of techniques, such as XRD, XPS, XRF, 29Si MAS NMR, 27Al MQ MAS NMR, FTIR, NH3-TPD, argon physisorption and HR-TEM, have been employed to decouple the interdependence between acidity, porosity and catalytic performance. It was found that mild HNO3 treatment could clean out the extra-framework aluminium deposits and selectively extract the aluminium species on the outer surface of Beta zeolites, which strengthened the acidity of the Brønsted acid sites (Si(OH)Al) inside the H-Beta micropores, thus increasing the possibility of intramolecular dehydration of E-BBA. Moreover, this mild HNO3 treatment also dredged the network of intercrystalline mesopores, alleviating the diffusion constraints. Therefore, through the dual adjustment of acidity and porosity, dealuminated H-Beta zeolite has a promising future in the green synthesis of 2-EAQ. Mild HNO3 treated nano-sized H-Beta zeolite showed outstanding catalytic activity, selectivity and reusability, compared with a commercial oleum catalyst. ![]()
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Affiliation(s)
- J. X. Liu
- State Key Laboratory of Fine Chemicals
- School of Chemical Engineering
- Dalian University of Technology
- Dalian
- China
| | - N. He
- State Key Laboratory of Fine Chemicals
- School of Chemical Engineering
- Dalian University of Technology
- Dalian
- China
| | - C. Y. Liu
- State Key Laboratory of Fine Chemicals
- School of Chemical Engineering
- Dalian University of Technology
- Dalian
- China
| | - G. R. Wang
- State Key Laboratory of Fine Chemicals
- School of Chemical Engineering
- Dalian University of Technology
- Dalian
- China
| | - Q. Xin
- State Key Laboratory for Catalysis
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
- Dalian 116023
- China
| | - H. C. Guo
- State Key Laboratory of Fine Chemicals
- School of Chemical Engineering
- Dalian University of Technology
- Dalian
- China
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Dai C, Cai XH, Cai YP, Guo HC, Sun W, Tan Q, Huang GH. An integrated simulation and optimization approach for managing human health risks of atmospheric pollutants by coal-fired power plants. J Air Waste Manag Assoc 2014; 64:704-720. [PMID: 25039204 DOI: 10.1080/10962247.2014.886639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
UNLABELLED This research developed a simulation-aided nonlinear programming model (SNPM). This model incorporated the consideration of pollutant dispersion modeling, and the management of coal blending and the related human health risks within a general modeling framework In SNPM, the simulation effort (i.e., California puff [CALPUFF]) was used to forecast the fate of air pollutants for quantifying the health risk under various conditions, while the optimization studies were to identify the optimal coal blending strategies from a number of alternatives. To solve the model, a surrogate-based indirect search approach was proposed, where the support vector regression (SVR) was used to create a set of easy-to-use and rapid-response surrogates for identifying the function relationships between coal-blending operating conditions and health risks. Through replacing the CALPUFF and the corresponding hazard quotient equation with the surrogates, the computation efficiency could be improved. The developed SNPM was applied to minimize the human health risk associated with air pollutants discharged from Gaojing and Shijingshan power plants in the west of Beijing. Solution results indicated that it could be used for reducing the health risk of the public in the vicinity of the two power plants, identifying desired coal blending strategies for decision makers, and considering a proper balance between coal purchase cost and human health risk. IMPLICATIONS A simulation-aided nonlinear programming model (SNPM) is developed. It integrates the advantages of CALPUFF and nonlinear programming model. To solve the model, a surrogate-based indirect search approach based on the combination of support vector regression and genetic algorithm is proposed. SNPM is applied to reduce the health risk caused by air pollutants discharged from Gaojing and Shijingshan power plants in the west of Beijing. Solution results indicate that it is useful for generating coal blending schemes, reducing the health risk of the public, reflecting the trade-offbetween coal purchase cost and health risk.
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Liu Y, Guo HC, Zou R, Wang LJ. Neural network modeling for regional hazard assessment of debris flow in Lake Qionghai Watershed, China. ACTA ACUST UNITED AC 2005. [DOI: 10.1007/s00254-005-0135-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Cheng ZX, Yi XJ, Han JR, Chen HC, Wang XL, Liu HK, Dou SX, Song F, Guo HC. Up-conversion luminescence of ytterbium and thulium codoped potassium yttrium double tungstate crystal. Cryst Res Technol 2002. [DOI: 10.1002/crat.200290008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Noumi H, Saha PK, Abe D, Ajimura S, Aoki K, Bhang HC, Endo T, Fujii Y, Fukuda T, Guo HC, Imai K, Hashimoto O, Hotchi H, Kim EH, Kim JH, Kishimoto T, Krutenkova A, Maeda K, Nagae T, Nakamura M, Outa H, Sekimoto M, Saito T, Sakaguchi A, Sato Y, Sawafta R, Shimizu Y, Takahashi T, Tang L, Tamura H, Tanida K, Watanabe T, Xia HH, Zhou SH, Zhu LH, Zhu XF. Sigma-nucleus potential in A=28. Phys Rev Lett 2002; 89:072301. [PMID: 12190516 DOI: 10.1103/physrevlett.89.072301] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2001] [Indexed: 05/23/2023]
Abstract
We have studied the (pi(-),K+) reaction on a silicon target to investigate the sigma-nucleus potential. The inclusive spectrum was measured at a beam momentum of 1.2 GeV/c with an energy resolution of 3.3 MeV (FWHM) by employing the superconducting kaon spectrometer system. The spectrum was compared with theoretical calculations within the framework of the distorted-wave impulse approximation, which demonstrates that a strongly repulsive sigma-nucleus potential with a nonzero size of the imaginary part reproduces the observed spectrum.
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Affiliation(s)
- H Noumi
- High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
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Shi XY, Guo HC, Wang M, Jiang SR. Capillary gas chromatography separation of pyrethroic acid methyl esters using four acylated cyclodextrin derivatives as chiral stationary phases. Chromatographia 2002. [DOI: 10.1007/bf02493213] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Guo HC, Liu L, Huang GH, Fuller GA, Zou R, Yin YY. A system dynamics approach for regional environmental planning and management: a study for the Lake Erhai Basin. J Environ Manage 2001; 61:93-111. [PMID: 11381461 DOI: 10.1006/jema.2000.0400] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In recent years, water-quality deterioration associated with rapid socio-economic development in the Lake Erhai Basin, China, has acquired more and more attention from the public and the government. An effective planning for the basin's environmental management system is desired for sustainable regional development. In this study, an environmental system dynamics model, named ErhaiSD, is developed for supporting this planning task. The ErhaiSD consists of dynamic simulation models that explicitly consider information feedback that governs interactions in the system. Such models are capable of synthesizing component-level knowledge into system behaviour simulation at an integrated level. This capability is very useful in analyzing and recommending policy decisions. For the study case, interactions among a umber of system components within a time frame of 15 years are examined dynamically. Four planning alternatives are considered. The base run is based on an assumption that the existing pattern of human activities will prevail in the entire planning horizon, and the other alternatives are based on previous planning studies. The contributions of various nonpoint pollution sources to the lake's eutrophication problems, and the effects of industrial activities and wastewater treatment processes on pollution problems in the Xier River are analyzed through the developed modeling system. The exercise draws attention to the implications of different alternatives to the system's environmental and socio-economic objectives. The modeling results are directly useful for simulating and evaluating a variety of decision actions and their dynamic consequences, and answering questions such as 'What should I do?', 'What if I do?' and 'What are the expected consequences?'.
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Affiliation(s)
- H C Guo
- Center of Environmental Sciences, Peking University, Key Laboratory for Water and Sediment Science, Ministry of Education, Beijing 100871, China
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O'Loughlin TJ, Xu Q, Kucera RB, Dorner LF, Sweeney S, Schildkraut I, Guo HC. Crystallization and preliminary X-ray diffraction analysis of MspI restriction endonuclease in complex with its cognate DNA. Acta Crystallogr D Biol Crystallogr 2000; 56:1652-5. [PMID: 11092936 DOI: 10.1107/s0907444900012713] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2000] [Accepted: 09/13/2000] [Indexed: 11/10/2022]
Abstract
The MspI restriction endonuclease is a type II restriction enzyme. Unlike all other restriction enzymes with known structures, MspI recognizes the palindromic tetranucleotide sequence 5'-C/CGG and cleaves it as indicated by the '/' to produce DNA products with 5' two-base overhangs. Owing to the nature of its cleavage pattern, it is likely that MspI would represent a new structural class of restriction endonucleases. Crystals of the dimeric MspI restriction enzyme bound to a duplex DNA molecule containing the specific recognition sequence have been obtained by vapor-diffusion techniques in the presence of polyethylene glycol as precipitant. The crystals belong to the monoclinic space group P2(1), with unit-cell parameters a = 50.2, b = 131.6, c = 59.3 A, beta = 109.7 degrees. The crystals contain one dimeric complex in the asymmetric unit. A complete native data set has been collected to a resolution of 2.05 A by cryo-crystallographic methods, with an R(merge) of 4.0%.
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Affiliation(s)
- T J O'Loughlin
- Department of Physiology and Structural Biology, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118-2526, USA
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Chen TH, Liao PH, Liao PY, Guo HC. Mutagenesis and expression of the E3-19k lumenal domain of adenovirus type 2. Kaohsiung J Med Sci 2000; 16:181-6. [PMID: 10933748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
CD8+ T cells recognize viral or tumor antigens of 8-10 residues derived from cytosolic proteins that are bound to the class I molecules of the major histocompatibility complex (MHC). To escape this immune surveillance, adenovirus expresses a protein, E3-19k, that specifically down-regulates the cell surface expression of class I MHC molecules on infected cells. To most effectively manipulate the T-cell response to virus-infected cells, it is essential to understand the mechanism by which viruses, such as adenoviruses, down-regulate the class I MHC function. We have subcloned the lumenal domain of adenovirus E3-19k protein in order to characterize its interactions with the class I MHC molecules. Several point mutations have also been generated on the E3-19k lumenal domain with either the first 96 or 108 amino acids. Attempts to crystallize the complexes between E3-19k and class I MHC molecule had been initiated.
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Cui T, Liao PH, Guan C, Guo HC. Purification and crystallization of precursors and autoprocessed enzymes of Flavobacterium glycosylasparaginase: an N-terminal nucleophile hydrolase. Acta Crystallogr D Biol Crystallogr 1999; 55:1961-4. [PMID: 10531509 DOI: 10.1107/s0907444999011798] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Glycosylasparaginase (GA) represents a novel group of proteins that are activated by self-catalyzed peptide-bond cleavage from a single-chain precursor to yield the two subunits required for hydrolase activity. The wild-type GA precursor autoproteolyzes spontaneously into alpha and beta subunits. Strategies are reported here for purification to homogeneity of GA from Flavobacterium meningosepticum in both single-chain precursor and mature (autoprocessed) forms. The recombinant proteins crystallize in different space groups: P1 and P2(1) for the precursor and mature enzymes, respectively. The precursor crystals diffract to 1.9 A resolution with laboratory X-ray radiation.
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Affiliation(s)
- T Cui
- New England Biolabs, 32 Tozer Road, Beverly, MA 01915-5599, USA
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13
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Abstract
A variety of proteins, including glycosylasparaginase, have recently been found to activate functions by self-catalyzed peptide bond rearrangements from single-chain precursors. Here we present the 1.9 A crystal structures of glycosylasparaginase precursors that are able to autoproteolyze via an N --> O acyl shift. Several conserved residues are aligned around the scissile peptide bond that is in a highly strained trans peptide bond configuration. The structure illustrates how a nucleophilic side chain may attack the scissile peptide bond at the immediate upstream backbone carbonyl and provides an understanding of the structural basis for peptide bond cleavage via an N --> O or N --> S acyl shift that is used by various groups of intramolecular autoprocessing proteins.
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Affiliation(s)
- Q Xu
- Department of Biophysics, Boston University School of Medicine, Massachusetts 02118-2526, USA
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Abstract
The crystal structures of class I major histocompatibility complex (MHC) molecules complexed with antigenic peptides revealed a network of hydrogen bonds between the charged amino- and carboxyl-termini of the peptides and conserved MHC residues at both ends of the peptide binding site. These interactions were shown to contribute substantially to the stability of class I MHC/peptide complexes by thermal denaturation studies using synthetic peptides in which either the amino- or carboxyl-terminal group is substituted by a methyl group. Here we report crystal structures of HLA-A*0201 complexed with these terminally modified synthetic peptides showing that they adopt the same bound conformation as antigenic peptides. A number of variations in peptide conformation were observed for the terminally modified peptides, including in one case, a large conformational difference in four central peptide residues that is apparently caused by the lattice contact. This is reminiscent of the way binding a T-cell receptor changed the conformation of central residues of an MHC-bound peptide. The structures determined identify which conserved hydrogen bonds are eliminated in terminally substituted peptides and suggest an increased energetic importance of the interactions at the peptide termini for MHC-peptide stability.
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Affiliation(s)
- M Bouvier
- Department of Molecular and Cellular Biology, Howard Hughes Medical Institute, Harvard University, Cambridge, Massachusetts 02138, USA
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Guo HC, Xu Q, Buckley D, Guan C. Crystal structures of Flavobacterium glycosylasparaginase. An N-terminal nucleophile hydrolase activated by intramolecular proteolysis. J Biol Chem 1998; 273:20205-12. [PMID: 9685368 DOI: 10.1074/jbc.273.32.20205] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycosylasparaginase (GA) is a member of a novel family of N-terminal nucleophile hydrolases that catalytically use an N-terminal residue as both a polarizing base and a nucleophile. These enzymes are activated from a single chain precursor by intramolecular autoproteolysis to yield the N-terminal nucleophile. A deficiency of GA results in the human genetic disorder known as aspartylglycosaminuria. In this study, we report the crystal structure of recombinant GA from Flavobacterium meningosepticum. Similar to the human structure, the bacterial GA forms an alphabetabetaalpha sandwich. However, some significant differences are observed between the Flavobacterium and human structures. The active site of Flavobacterium glycosylasparaginase is in an open conformation when compared with the human structure. We also describe the structure of a mutant wherein the N-terminal nucleophile Thr152 is substituted by a cysteine. In the bacterial GA crystals, we observe a heterotetrameric structure similar to that found in the human structure, as well as that observed in solution for eukaryotic glycosylasparaginases. The results confirm the suitability of the bacterial enzyme as a model to study the consequences of mutations in aspartylglycosaminuria patients. They also suggest that further studies are necessary to understand the detail mechanism of this enzyme. The presence of the heterotetrameric structure in the crystals is significant because dimerization of precursors has been suggested in the human enzyme to be a prerequisite to trigger autoproteolysis.
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Affiliation(s)
- H C Guo
- Department of Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118-2526, USA.
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Abstract
We have constructed a ribozyme containing 144 nucleotides of Neurospora VS RNA that can catalyze the cleavage of a separate RNA in a true enzymatic manner (Km approximately 0.13 microM, kcat approximately 0.7/min). Comparison of the rates of cis- and trans-cleavage, as well as the lack of effect of pH on the rate of cleavage, suggest that a rate-limiting step, possibly a conformational change, occurs prior to cleavage. The minimum contiguous substrate sequence required for cleavage consists of one nucleotide upstream and 19 nucleotides downstream of the cleavage site. Unlike most other ribozymes which interact with long single-stranded regions of their substrates, the minimal substrate for the VS ribozyme consists mostly of a stable stem-loop, which would appear to preclude its recognition simply via extensive Watson-Crick base pairing.
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Affiliation(s)
- H C Guo
- Canadian Institute for Advanced Research Program in Evolutionary Biology, University of Toronto, Ontario
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Guo HC, Madden DR, Silver ML, Jardetzky TS, Gorga JC, Strominger JL, Wiley DC. Comparison of the P2 specificity pocket in three human histocompatibility antigens: HLA-A*6801, HLA-A*0201, and HLA-B*2705. Proc Natl Acad Sci U S A 1993; 90:8053-7. [PMID: 8367462 PMCID: PMC47286 DOI: 10.1073/pnas.90.17.8053] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Coordinates from x-ray structures of HLA-A*6801, HLA-A*0201, and HLA-B*2705 were analyzed to examine the basis for their selectivity in peptide binding. The pocket that binds the side chain of the peptide's second amino acid residue (P2 residue) shows a preference for Val, Leu, and Arg in these three HLA subtypes, respectively. The Arg-specific pocket of HLA-B*2705 differs markedly from those of HLA-A*0201 and HLA-A*6801, as a result of numerous differences in the side chains that form the pocket's surface. The cause of the specificity differences between HLA-A*0201 and HLA-A*6801 is more subtle and depends both on a change in conformation of pocket residue Val-67 and on a sequence difference at residue 9. The Val-67 conformational change appears to be caused by a shift in the position of the alpha 1-domain alpha-helix relative to the beta-sheet in the cleft and may, in fact, depend on amino acid differences remote from the P2 pocket. Analysis of the stereochemistry of the P2 side chain interacting with its binding pocket permits an estimate to be made of its contribution to the free-energy change of peptide binding.
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Affiliation(s)
- H C Guo
- Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, MA
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Abstract
We have used several complementary approaches to investigate the minimal contiguous sequence required for the in vitro self cleavage reaction performed by Neurospora VS RNA. Deletion analysis and site-directed mutagenesis revealed that only a single nucleotide is required upstream of the self-cleavage site, and that the identity of this nucleotide is not critical. This distinguishes VS RNA from all currently known ribozymes except hepatitis delta virus RNA. The shortest contiguous sequence capable of cleavage contains 153 nt downstream of the cleavage site. Linker insertion mutagenesis suggests that much of this downstream sequence is important for self-cleavage. Comparative sequence analysis of the VS plasmid from six natural isolates supports the importance in vivo of the minimal region determined by in vitro methods. Also, phylogenetic analysis raises the possibility of a recent horizontal transfer of the VS plasmid from Neurospora intermedia to Neurospora sitophila.
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Affiliation(s)
- H C Guo
- Department of Molecular and Medical Genetics, University of Toronto, Ontario, Canada
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Abstract
Infection by influenza virus results in the stimulation of cytotoxic T lymphocytes specific for killing virally infected cells. Specificity is provided by clonally distributed, hypervariable T-cell receptors on cytotoxic T lymphocytes which react with peptide fragments that are derived from viral proteins expressed in the cytoplasm and 'presented' on the surface of infected cells, bound to class I histocompatibility glycoproteins. Here we describe the structure of the complex between the human class I histocompatibility glycoprotein HLA-Aw68 and the influenza virus nucleoprotein peptide Np 91-99 as determined by X-ray cryocrystallography. Residues at both ends of the peptide are substantially buried in the peptide binding-site, whereas those in the middle of the peptide, P4 to P8, are predominantly exposed and could be recognized directly by T-cell receptors. The extended conformation of the bound viral peptide is remarkably similar to that of a collection of endogenous peptides with a different sequence motif bound to another human allele, HLA-B27. The structure defines in atomic detail the antigenic surface constructed of major histocompatibility complex and viral peptide atoms that is recognized by T-cell receptors.
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Affiliation(s)
- M L Silver
- Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138
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Guo HC, Jardetzky TS, Garrett TP, Lane WS, Strominger JL, Wiley DC. Different length peptides bind to HLA-Aw68 similarly at their ends but bulge out in the middle. Nature 1992; 360:364-6. [PMID: 1448153 DOI: 10.1038/360364a0] [Citation(s) in RCA: 315] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We report here the determination and refinement to 1.9 A resolution by X-ray cryo-crystallography the structure of HLA-Aw68. The averaged image from the collection of bound, endogenous peptides clearly shows the atomic structure at the first three and last two amino acids in the peptides but no connected electron density in between. This suggests that bound peptides, held at both ends, take alternative pathways and could be of different lengths by bulging out in the middle. Peptides eluted from HLA-Aw68 include peptides of 9, 10 and 11 amino acids, a direct indication of the length heterogeneity of tightly bound peptides. Peptide sequencing shows relatively conserved 'anchor' residues at position 2 and the carboxy-terminal residue. Conserved binding sites for the peptide N and C termini at the ends of the class I major histocompatibility complex binding groove are apparently dominant in producing the long half-lives of peptide binding and the peptide-dependent stabilization of the class I molecule's structure.
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Affiliation(s)
- H C Guo
- Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138
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Guo HC, Michel JB, Blouquit Y, Chapman MJ. Lipoprotein(a) and apolipoprotein(a) in a New World monkey, the common marmoset (Callithrix jacchus). Association of variable plasma lipoprotein(a) levels with a single apolipoprotein(a) isoform. Arterioscler Thromb 1991; 11:1030-41. [PMID: 1829630 DOI: 10.1161/01.atv.11.4.1030] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In an earlier report (Chapman et al, Biochemistry 1979;18:5096-5108), we suggested that the common marmoset may represent an important model for the study of human plasma lipoprotein metabolism. We now extend the interest of this monkey model to the study of lipoprotein(a) (Lp[a]) and apolipoprotein(a) (apo[a]). Density gradient ultracentrifugal fractionation of marmoset plasma revealed a bimodal distribution of Lp(a), with one peak of concentration occurring in association with very low density lipoproteins (VLDLs) and a second in the density range 1.040-1.080 g/ml. The dense Lp(a) subspecies displayed physicochemical properties (chemical composition, particle size, and electrophoretic mobility) that closely resembled those of its counterpart in humans and baboons but that were distinct from those of low density lipoprotein (LDL). Furthermore, the particle size of marmoset Lp(a) was invariant (31 nm) over the density interval 1.040-1.080 g/ml, whereas that of LDL decreased progressively with an increase in density (approximately 26-25.2 nm). Use of polyclonal and monoclonal antibodies to human apo(a) and of a polyclonal antibody to marmoset Lp(a) allowed immunologic identification of a single apo(a) isoform in the marmoset whose size was similar to that of apo B-100; apo(a) and apo B-100 were associated in Lp(a) particles by a disulfide linkage. The total protein mass of apo-Lp(a) was estimated to be 800,000 or more by electrophoresis in sodium dodecyl sulfate-polyacrylamide-agarose gels. The amino acid compositions of marmoset and human apo(a) resembled each other but were distinct from those of the corresponding forms of apo B-100. Immunologic evidence is provided for a high degree of cross reactivity between apo(a) in marmosets, baboons, and humans, supporting the idea of the existence of a marked degree of structural homology between these proteins. In addition, electroimmunoblotting of marmoset apo(a) and marmoset plasminogen showed that these proteins shared certain epitopes in common, suggesting that marmoset apo(a) may possess kringle-like structural features. Finally, despite possession of a single apo(a) isoform, marmoset Lp(a) levels varied over a 100-fold range (0.5-49 mg/dl plasma). Considered together, our present findings suggest that the common marmoset monkey constitutes a unique model in which to study the regulation of apo(a) gene expression and the posttranslational processing of apo(a), as well as factors that modulate the synthesis, intravascular metabolism, and cellular catabolism of Lp(a).
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Affiliation(s)
- H C Guo
- INSERM Unité 321, Hôpital de la Pitié, Paris, France
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Abstract
A segment of Escherichia coli bacteriophage 21 DNA encoding the late-gene regulator, Q21, and the late-gene leader RNA segment was sequenced; its structure is similar to those of the related phages lambda and 82. The leader RNA is about 45 nucleotides long and consists essentially entirely of sequences encoding the p-independent terminator that is the putative target of the antitermination activity of Q21. Like the corresponding regions of lambda and 82, the 21 late-gene promoter segment encodes an early transcription pause in vitro, at about nucleotide 18, during which Q21 presumably acts to modify RNA polymerase. The 21 Q gene, cloned in isolation, is active on the late-gene leader segment in trans, and its purified product is active as an antiterminator in vitro; Q21 represents a third late-gene antiterminator, in addition to those of lambda and 82. There is little evident similarity in the primary sequences of the three Q genes.
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Affiliation(s)
- H C Guo
- Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853
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23
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Guo HC, Chapman MJ, Bruckert E, Farriaux JP, De Gennes JL. Lipoprotein Lp(a) in homozygous familial hypercholesterolemia: density profile, particle heterogeneity and apolipoprotein(a) phenotype. Atherosclerosis 1991; 86:69-83. [PMID: 1829609 DOI: 10.1016/0021-9150(91)90100-h] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Homozygous familial hypercholesterolemia (FH) is a genetic disorder featuring a functional defect in cellular LDL receptors, marked elevation in circulating LDL concentrations, and premature atherosclerosis. The potential atherogenic role of apo B-containing lipoproteins other than LDL in this disease is indeterminate. We describe the quantitative and qualitative characteristics of Lp(a) as a function of apo(a) phenotype in a group of eight, unrelated homozygous FH patients. Plasma Lp(a) levels were significantly elevated (2.5-fold; mean 50 +/- 32 mg/dl) as compared to those in healthy subjects. The S2 isoform of apo(a) occurred most frequently (6 of eight patients); the rare B isoform presented in three patients. Plasma Lp(a) levels in homozygous FH did not correspond to those predicted by apo(a) phenotype. Analyses of the density distribution of Lp(a) and of Lp(a) particle size and heterogeneity as a function of density did not reveal any anomalies characteristic of homozygous FH. However, comparison of the hydrated density of Lp(a) particles as a function of apo(a) isoform content revealed a clear influence of isoform on this parameter; thus, in a B/S2 heterozygous patient, the density distribution of Lp(a) fractions containing isoform B alone, B and S2, and S2 alone, demonstrated that the apparent molecular weight of apo(a) plays a determining role in controlling the hydrated density and size of the resulting Lp(a) particle. Indeed, patients expressing the high molecular weight, S2 isoform uniformly displayed a dense form of Lp(a) (hydrated density approximately 1.055 g/ml). In subjects presenting two apo(a) isoforms, each isoform resided on distinct lipoprotein particles; in such cases, the plasma levels of the denser isoform predominated, suggesting differences in rates of formation, or rates of tissular catabolism, or in the plasma stability of the particles, or a combination of these mechanisms. Considered together, our data may be interpreted to suggest that the elevated circulating levels of Lp(a) in homozygous FH patients may reflect either an increased biosynthesis, or diminished catabolism via the cellular LDL receptor pathway, or a combination of both.
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Affiliation(s)
- H C Guo
- Lipoprotein and Atherogenesis Research Unit, INSERM U.321, Hôpital de la Pitié, Paris
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24
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Abstract
RNAs synthesized in vitro by purified Escherichia coli RNA polymerase from a bacteriophage 82 promoter are heterogeneous at the 5' end. We show that this heterogeneity results from variable addition of extra adenine residues, allowed by slippage of the initial oligonucleotide pppAAA-OH against its DNA template sequence TTT. Slippage backward by one base allows another A to be added, giving pppAAAA-OH, and this cycle can continue more than 20 times before it is ended by incorporation of UMP encoded by the fourth template base A. Slippage is abolished by mutation of the TTT template sequence to TGT and is sensitive to the concentrations of UTP and ATP in the reaction mixture. Analysis of deletions, substitutions, and point mutants implies that the slippage reaction requires only the existence of TTT at the initiation site of the template strand, although changes in neighboring nucleotides slightly affect its efficiency.
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Affiliation(s)
- H C Guo
- Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853
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25
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Abstract
We have constructed novel transcription templates in which we have fused the late gene promoters of Escherichia coli phages lambda and 82 upstream from three different rho-independent transcription terminators. Using an in vitro transcription assay and an in vivo galactokinase expression assay, we find that the initial portion of the transcribed region significantly affects the efficiency of some downstream terminators. We have identified, by deletion, substitution and point mutation analysis, sequences responsible for these increased levels of factor-independent readthrough. Since these important sequences occur within about 30 nucleotides of the RNA start site, we suggest that the initial portion of the transcript can affect termination efficiency.
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Affiliation(s)
- J A Goliger
- Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, NY 14853
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26
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Guo HC, Armstrong VW, Luc G, Billardon C, Goulinet S, Nustede R, Seidel D, Chapman MJ. Characterization of five mouse monoclonal antibodies to apolipoprotein[a] from human Lp[a]: evidence for weak plasminogen reactivity. J Lipid Res 1989; 30:23-37. [PMID: 2521888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We describe the development of five murine monoclonal antibodies (14A12, 39A1, 53A9, 73A7, and 128A6) specific to human apolipoprotein[a] (Mr approximately 570,000), and their characterization by a number of procedures including cotitration, competition and inhibition enzyme-linked immunosorbent assays (ELISA), immunoblotting of native lipoproteins and of SDS-solubilized apolipoproteins electrophoresed in polyacrylamide gels, and dot immunobinding assays. The patterns of immunoreactivity of these antibodies were similar. Each reacted in ELISA assays and upon electroimmunoblotting with purified apo[a], with apo[a] liberated by reduction of Lp[a], and with delipidated Lp[a] solubilized in SDS, but by contrast, they reacted with native Lp[a] to a significant degree only upon electroimmunoblotting. No reactivity was seen with LDL-apoB-100 or with other apolipoproteins. The cross-reactivity of these antibodies with the homologous protein, plasminogen, was examined by comparison of the amount of plasminogen or apo[a] required for 50% inhibition of antibody binding to apo[a], and by an ELISA assay. The inhibition assay showed reactivity with plasminogen to be 37- to 50-fold lower than with apo[a], while dot immunobinding showed the lower limit of detection of plasminogen and of apo[a] to be approximately 320 and 31 micrograms, respectively. In an ELISA sandwich assay based on monoclonal antibodies LHLP-1, 14A12, and 53A9, the lower limit of Lp[a] detection (approximately 1 ng/ml protein) was about 100-fold less than that of plasminogen. Chemical modification of apo[a] revealed a significant contribution of arginine residues to the epitopes of 14A12, 39A1, and 53A9. Modification of cysteine residues with iodoacetamide was without effect, thereby distinguishing these antibodies from LHLP-1. Each antibody reacted with the six major size forms of apo[a] (Mr approximately 450,000-750,000) in immunoblots of human sera electrophoresed in SDS-polyacrylamide gels. Marked heterogeneity in apo[a] phenotype was detected and both single and double band phenotypes were observed in a randomized study. Cotitration and competition binding studies showed varying degrees of interaction between all five epitopes, with the exception of 128A6 which appeared to be independent of 39A1 and 53A9 (and vice versa). These data suggest that our five monoclonal antibodies recognize epitopes on apolipoprotein[a] that are exposed and accessible on the native Lp[a] particle. We conclude that our monoclonal antibodies recognize a specific region of apo[a], and that this region undergoes a conformational change upon adsorption of Lp[a] to plastic thereby diminishing epitope recognition.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- H C Guo
- Groupe de Recherches INSERM sur les Lipoprotéines, Hôpital de la Pitié, Paris, France
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27
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Guo HC, Armstrong VW, Luc G, Billardon C, Goulinet S, Nustede R, Seidel D, Chapman MJ. Characterization of five mouse monoclonal antibodies to apolipoprotein[a] from human Lp[a]: evidence for weak plasminogen reactivity. J Lipid Res 1989. [DOI: 10.1016/s0022-2275(20)38392-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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28
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Di JD, Zhu YK, Li YC, Wang GL, Guo HC. New surgical approach in pediatric femoral head avascular necrosis. Chin Med J (Engl) 1982; 95:31-9. [PMID: 6802578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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