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On welfare pluralism, social policy and the contribution of sociology: Revisiting Robert Pinker. FRONTIERS IN SOCIOLOGY 2023; 8:1076750. [PMID: 37139226 PMCID: PMC10149760 DOI: 10.3389/fsoc.2023.1076750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/20/2023] [Indexed: 05/05/2023]
Abstract
On occasion it makes sound sense to undertake a retrospective review of a late colleague's contribution to his or her subject area. This applies to Robert Pinker, Professor of Social Administration at the London School of Economics, who died at the age of 89 in February 2021. Over a long life he made a major impact on working for press freedom and to social work studies, but this article concerns his work on social policy, and particularly on the idea of welfare pluralism, a many-faceted idea the exploration of which powered two pathbreaking books Social Theory and Social Policy (1971) and The Idea of Welfare (1979). In the twentieth century many states including the United Kingdom had greatly expanded their welfare provisions for their citizens, and, in some, an academic subject area, often called social administration or social policy had grown in response. Pinker started writing in the 1960s, dissatisfied with the conventional approach of Richard Titmuss and others, almost exclusively concerned with the state and welfare. He made the case for a radical rebalance toward including everyday experiences of obligations and how familial informal welfare practices are strengthened, weakened or modified by formal social services. However, ahead of his time, Pinker was arguing for an enhanced sociological imagination in the study of social policy and on the very idea of "welfare". This article has sections reflecting the facets of Pinker's thinking about welfare pluralism, including "social policy's past", "exchange and stigma", "taking informal welfare seriously", "divergent views of altruism", "comparative studies", "on a mixture of means to welfare" and "aspects of Pinker's legacy". The idea of welfare pluralism is now familiar. But Pinker's crucial pioneering role, depth of understanding of the issues and grasp of their intertwining is seldom recalled. This article should help to meet the need for his contribution to be reinserted into the mainstream of sociological thought on welfare, so enriching new research.
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Abstract
Solubility is a key property of peptides and of central importance to the success of solid-phase peptide synthesis and subsequent peptide purification and handling. Substitution of the backbone amide bond can dramatically increase peptide solubility. Backbone amide bond protection works by preventing the formation of interchain association and can be used both to synthesize aggregation-prone peptide sequences on solid phase and to improve solubility of a peptide post synthesis. Improving peptide solubility by judicial use of backbone protection is of growing importance, particularly for chemical protein synthesis by chemical ligation.
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Herbert Spencer, Sociological Theory, and the Professions. FRONTIERS IN SOCIOLOGY 2019; 4:77. [PMID: 33869399 PMCID: PMC8022487 DOI: 10.3389/fsoc.2019.00077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 11/13/2019] [Indexed: 06/12/2023]
Abstract
This article presents new insights into Spencer's theoretical sociology as he applied it to the professions and professional institutions, which he discussed extensively, particularly in his Principles of Sociology. The first part of this article notes the main conceptual insights which he established and aligns them within the wider context of a re-reading of Spencer's sociology. Particular attention is paid to the "social organism" and the spontaneous cooperation of social individuals in society (with each possessing "social self-consciousness"). This part also reappraises Spencer's account of the emergence of "professionals" and their distinctive "cunning, skill, and acquaintance with the nature of things," which professionals have brought to bear on what has been experienced in the ordinary social lives of people as complexity or the unfamiliar in the world. The subsequent discussion focuses on, first, a retrieval of Spencer's theoretical stance on the activities of the professions, and on work and conditions in general, and, second, on reviewing some of the major resonances which his work has with practical problems and the associated theoretical issues concerning the sociological understanding of professional/service-user interaction in social life today.
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Head to tail cyclisation of cell-penetrating peptides: impact on GAG-dependent internalisation and direct translocation. Chem Commun (Camb) 2019; 55:4566-4569. [PMID: 30931466 DOI: 10.1039/c9cc01265f] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A series of cyclic lipidated oligo-Arg cell penetrating peptides were synthesised with varied macrocycle size and lipid chain anchoring site. The study of their cellular uptake revealed different structural requirements to promote efficient glycosaminoglycan-dependent endocytosis and direct translocation.
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Social Solidarity and Herbert Spencer: Not the Oxymoron That Might Be Assumed. FRONTIERS IN SOCIOLOGY 2019; 4:1. [PMID: 33869330 PMCID: PMC8022655 DOI: 10.3389/fsoc.2019.00001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 01/07/2019] [Indexed: 06/12/2023]
Abstract
This article attempts to retrieve important aspects of Spencer's sociology from the general neglect and misrepresentation which threatens to overwhelm it all. It does touch in passing on many such highly dubious contentions as that he was a "social Darwinist," but the prime focus is to deal with three linked themes. First, the article examines the significance of his attribution to individuals of "social self-consciousness" as part of sociality, thus distancing it from Durkheim's influential but suspect reading of Spencer's individuals as egoistic. Second, it rescues his concept of "the social organism" from misinterpretation. His own writings show it to be a more rigorous and suggestive attempt to configure the morphology of "the social" than commonly assumed. Third, it reconstructs the status of his contrast between "militant" and "industrial" social forms as a contrast between different but more general forms of social life that those descriptions in fact register. With the focus on these three linked themes the article improves the historical accuracy of our understanding of Spencer's sociology. It also repositions key aspects of it as not alien, quaint and a spent force, but ontologically challenging and possibly prescient for debates about the meaning of "the social" today.
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A method for the unbiased and efficient segmental labelling of RNA-binding proteins for structure and biophysics. Sci Rep 2017; 7:14083. [PMID: 29074846 PMCID: PMC5658380 DOI: 10.1038/s41598-017-13950-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 10/03/2017] [Indexed: 01/05/2023] Open
Abstract
Most eukaryotic RNA regulators recognise their RNA and protein partners by the combinatorial use of several RNA binding domains. Inter-domain dynamics and interactions play a key role in recognition and can be analysed by techniques such as NMR or FRET, provided that the information relative to the individual interactions can be de-convoluted. Segmentally labelling the proteins by ligating labelled and unlabelled peptide chains allows one to filter out unwanted information and observe the labelled moieties only. Several strategies have been implemented to ligate two protein fragments, but multiple ligations, which are necessary to segmentally label proteins of more than two domains, are more challenging and often dependent on the structure and solubility of the domains. Here we report a method to ligate multiple protein segments that allows the fast, high yield labelling of both internal and end domains, depending on the requirements. We use TCEP and mercaptophenylacetic acid (MPAA) in an optimised reaction environment to achieve an efficient ligation of protein domains independently from their structure or solubility. We expect the method will provide a useful tool for the molecular study of combinatorial protein–RNA recognition in RNA regulation.
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Abstract
We have developed a convenient method for the direct synthesis of peptide thioesters, versatile intermediates for peptide ligation and cyclic peptide synthesis. The technology uses a modified Boc SPPS strategy that avoids the use of anhydrous HF. Boc in situ neutralization protocols are used in combination with Merrifield hydroxymethyl resin and TFA/TMSBr cleavage. Avoiding HF extends the scope of Boc SPPS to post-translational modifications that are compatible with the milder cleavage conditions, demonstrated here with the synthesis of the phosphorylated protein CHK2. Peptide thioesters give easy, direct, access to cyclic peptides, illustrated by the synthesis of cyclorasin, a KRAS inhibitor.
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A backbone amide protecting group for overcoming difficult sequences and suppressing aspartimide formation. J Pept Sci 2016; 22:360-7. [PMID: 27086749 PMCID: PMC5074248 DOI: 10.1002/psc.2877] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 02/18/2016] [Accepted: 02/29/2016] [Indexed: 12/01/2022]
Abstract
A backbone amide bond protecting group, 2‐hydroxy‐4‐methoxy‐5‐nitrobenzyl (Hmnb), improved the synthesis of aggregation and aspartimide‐prone peptides. Introduction of Hmnb is automated and carried out during peptide assembly by addition of 4‐methoxy‐5‐nitrosalicylaldehyde to the peptidyl‐resin and on‐resin reduction to the secondary amine. Acylation of the hindered secondary amine is aided by the formation of an internal nitrophenol ester that undergoes a favourable O,N intramolecular acyl transfer. This activated ester participates in the coupling and generally gives complete reaction with standard coupling conditions. Hmnb is easily available in a single preparative step from commercially available material. Different methods for removing the amide protecting group were explored. The protecting group is labile to acidolysis, following reduction of the nitro group to the aniline. The two main uses of backbone protection of preventing aspartimide formation and of overcoming difficult sequences are demonstrated, first with the synthesis of a challenging aspartimide‐prone test sequence and then with the classic difficult sequence ACP (65‐74) and a 23‐mer homopolymer of polyalanine.
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Abstract
Today, Fmoc SPPS is the method of choice for peptide synthesis. Very-high-quality Fmoc building blocks are available at low cost because of the economies of scale arising from current multiton production of therapeutic peptides by Fmoc SPPS. Many modified derivatives are commercially available as Fmoc building blocks, making synthetic access to a broad range of peptide derivatives straightforward. The number of synthetic peptides entering clinical trials has grown continuously over the last decade, and recent advances in the Fmoc SPPS technology are a response to the growing demand from medicinal chemistry and pharmacology. Improvements are being continually reported for peptide quality, synthesis time and novel synthetic targets. Topical peptide research has contributed to a continuous improvement and expansion of Fmoc SPPS applications.
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Abstract
The automated introduction of removable substitution along a peptide backbone prevents chain-association and synthesis failure.
The synthesis of peptides rich in aggregation prone sequences can be improved with backbone protection. We report the automated introduction of backbone protection to a peptide. This new method was applied in a fully-automated synthesis, giving improved handling, quality and yield of several challenging target sequences.
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Jarid2 Methylation via the PRC2 Complex Regulates H3K27me3 Deposition during Cell Differentiation. Mol Cell 2015; 57:769-783. [PMID: 25620564 PMCID: PMC4352895 DOI: 10.1016/j.molcel.2014.12.020] [Citation(s) in RCA: 190] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 08/01/2014] [Accepted: 12/12/2014] [Indexed: 02/06/2023]
Abstract
Polycomb Group (PcG) proteins maintain transcriptional repression throughout development, mostly by regulating chromatin structure. Polycomb Repressive Complex 2 (PRC2), a component of the Polycomb machinery, is responsible for the methylation of histone H3 lysine 27 (H3K27me2/3). Jarid2 was previously identified as a cofactor of PRC2, regulating PRC2 targeting to chromatin and its enzymatic activity. Deletion of Jarid2 leads to impaired orchestration of gene expression during cell lineage commitment. Here, we reveal an unexpected crosstalk between Jarid2 and PRC2, with Jarid2 being methylated by PRC2. This modification is recognized by the Eed core component of PRC2 and triggers an allosteric activation of PRC2’s enzymatic activity. We show that Jarid2 methylation is important to promote PRC2 activity at a locus devoid of H3K27me3 and for the correct deposition of this mark during cell differentiation. Our results uncover a regulation loop where Jarid2 methylation fine-tunes PRC2 activity depending on the chromatin context. PRC2 methylates Jarid2 on K116 Jarid2 methylation promotes PRC2 activity H3K27me3 and Jarid2-K116me3 bind to the aromatic cage of Eed Jarid2 methylation regulates H3K27me3 deposition during ESC differentiation
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Abstract
Protein-ligand complex neocarzinostatin (NCS) is a small, thermostable protein-ligand complex that is able to deliver its ligand cargo into live mammalian cells where it induces DNA damage. Apo-NCS is able to functionally display complementarity determining regions loops, and has been hypothesised to act as a cell-penetrating protein, which would make it an ideal scaffold for cell targeting, and subsequent intracellular delivery of small-molecule drugs. In order to evaluate apo-NCS as a cell penetrating protein, we have evaluated the efficiency of its internalisation into live HeLa cells using matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry and fluorescence microscopy. Following incubation of cells with apo-NCS, we observed no evidence of internalisation.
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Simplifying native chemical ligation with an N-acylsulfonamide linker. Chem Commun (Camb) 2012; 48:2579-81. [DOI: 10.1039/c2cc15911b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Chemical labelling of active serum thioester proteins for quantification. Immunobiology 2011; 217:256-64. [PMID: 21852021 PMCID: PMC3274692 DOI: 10.1016/j.imbio.2011.07.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Revised: 07/08/2011] [Accepted: 07/18/2011] [Indexed: 11/19/2022]
Abstract
The complement serum proteins C3 and C4 and the protease inhibitor α-2 macroglobulin are all members of the C3/α-2M thioester protein family, an evolutionarily ancient and conserved family that contains an intrachain thioester bond. The chemistry of the thioester bond is a key to the function of the thioester proteins. All these proteins function by covalently linking to their target by acyl transfer of the protein via the thioester moiety. We show that the signature thioester bond can be targeted with nucleophiles linked to a bioreporter molecule, site-specifically modifying the whole, intact thioester protein. Conditions were optimised to label selectively and efficiently pull-down unprocessed thioester-containing proteins from serum. We demonstrated pull-down of full-length C3, α-2M and C4 from sera in high salt, using a biotinylated nucleophile and streptavidin-coated resin, confirmed by MALDI-TOF MS identification of the gel bands. The potential for the development of a quantitative method for measuring active C3 in serum was investigated in patient sera pre and post operation. Quantifying active C3 in clinical assays using current methods is difficult. Methods based on antibody detection (e.g. nephelometry) do not distinguish between active C3 and inactive breakdown products. C3-specific haemolytic assays can be used, but these require use of relatively unstable reagents. The current work represents a promising robust, enzyme- and antibody-free chemical method for detecting active thioester proteins in blood, plasma or serum.
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The influence of different lipid environments on the structure and function of the hepatitis C virus p7 ion channel protein. Mol Membr Biol 2011; 28:254-64. [DOI: 10.3109/09687688.2011.581253] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Cholesterol secosterol adduction inhibits the misfolding of a mutant prion protein fragment that induces neurodegeneration. Angew Chem Int Ed Engl 2010; 48:9469-72. [PMID: 19899085 DOI: 10.1002/anie.200904524] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Cholesterol Secosterol Adduction Inhibits the Misfolding of a Mutant Prion Protein Fragment that Induces Neurodegeneration. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200904524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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A Chemical Approach to Immunoprotein Engineering: Chemoselective Functionalization of Thioester Proteins in Their Native State. Chembiochem 2009; 10:1340-3. [DOI: 10.1002/cbic.200900168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Cover Picture: A Chemical Approach to Immunoprotein Engineering: Chemoselective Functionalization of Thioester Proteins in Their Native State (ChemBioChem 8/2009). Chembiochem 2009. [DOI: 10.1002/cbic.200990027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Cholesterolseco-Sterol-Induced Aggregation of Methylated Amyloid-β Peptides—Insights into Aldehyde-Initiated Fibrillization of Amyloid-β. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200705922] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Cholesterolseco-Sterol-Induced Aggregation of Methylated Amyloid-β PeptidesâInsights into Aldehyde-Initiated Fibrillization of Amyloid-β. Angew Chem Int Ed Engl 2008; 47:3919-22. [DOI: 10.1002/anie.200705922] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Orthogonal ligation: a three piece assembly of a PNA-peptide-PNA conjugate. Chem Commun (Camb) 2008:2785-7. [PMID: 18688310 DOI: 10.1039/b801242c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A PNA-peptide-PNA conjugate was assembled from three fragments using a combination of native chemical ligation and an orthogonal, auxiliary-mediated ligation.
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Crystal structures of histone demethylase JMJD2A reveal basis for substrate specificity. Nature 2007; 448:87-91. [PMID: 17589501 DOI: 10.1038/nature05971] [Citation(s) in RCA: 257] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Accepted: 06/04/2007] [Indexed: 11/09/2022]
Abstract
Post-translational histone modification has a fundamental role in chromatin biology and is proposed to constitute a 'histone code' in epigenetic regulation. Differential methylation of histone H3 and H4 lysyl residues regulates processes including heterochromatin formation, X-chromosome inactivation, genome imprinting, DNA repair and transcriptional regulation. The discovery of lysyl demethylases using flavin (amine oxidases) or Fe(II) and 2-oxoglutarate as cofactors (2OG oxygenases) has changed the view of methylation as a stable epigenetic marker. However, little is known about how the demethylases are selective for particular lysyl-containing sequences in specific methylation states, a key to understanding their functions. Here we reveal how human JMJD2A (jumonji domain containing 2A), which is selective towards tri- and dimethylated histone H3 lysyl residues 9 and 36 (H3K9me3/me2 and H3K36me3/me2), discriminates between methylation states and achieves sequence selectivity for H3K9. We report structures of JMJD2A-Ni(II)-Zn(II) inhibitor complexes bound to tri-, di- and monomethyl forms of H3K9 and the trimethyl form of H3K36. The structures reveal a lysyl-binding pocket in which substrates are bound in distinct bent conformations involving the Zn-binding site. We propose a mechanism for achieving methylation state selectivity involving the orientation of the substrate methyl groups towards a ferryl intermediate. The results suggest distinct recognition mechanisms in different demethylase subfamilies and provide a starting point to develop chemical tools for drug discovery and to study and dissect the complexity of reversible histone methylation and its role in chromatin biology.
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Abstract
The sustained effort towards developing an antibody vaccine against HIV/AIDS has provided much of our understanding of viral immunology. It is generally accepted that one of the main barriers to antibody neutralization of HIV is the array of protective structural carbohydrates that covers the antigens on the virus's surface. Intriguingly, however, recent findings suggest that these carbohydrates, which have evolved to protect HIV and promote its transmission, are also attractive therapeutic targets.
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An o-nitrobenzyl scaffold for peptide ligation: synthesis and applications. Bioorg Med Chem 2004; 12:2749-57. [PMID: 15110856 DOI: 10.1016/j.bmc.2004.02.039] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2003] [Revised: 02/24/2004] [Accepted: 02/27/2004] [Indexed: 11/30/2022]
Abstract
Chemical ligation approaches facilitate the chemoselective assembly of unprotected peptides in aqueous solution. Here, two photolabile auxiliaries are described that enlarge the applicability of native chemical ligation to non-cysteine targets. The auxiliaries, designed to allow reaction with thioester peptides, generate an amide bond between the two initial fragments. The o-nitrobenzyl tertiary benzylamide that is formed at the ligation junction can be transformed into a native amide group under mild photolysis conditions. The veratryl auxiliary was found to be excessively labile during peptide purification and ligation. However, the auxiliary based on the o-nitrobenzyl group shows all the necessary properties for a general application in routine peptide and protein synthesis. In addition, the auxiliary linked to the N-terminus can be efficiently photolyzed, suggesting a new approach for the generation of photocaged amines. Synthesis, solid phase introduction onto peptide chains, ligation properties and photolysis in water are described, and a careful study of compatibility of the method with potentially fragile peptide side chains is reported.
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Abstract
Immobilized metal affinity chromatography (IMAC) has rapidly become one of the most widespread affinity purification techniques employed in recombinant protein expression. However, the high purity demands of certain applications are occasionally unattainable through a single IMAC separation. GNC92H2scFv is a cocaine-binding single-chain antibody fragment that is unstable during long-term storage in aqueous solution. To circumvent this problem, a reversed-phase HPLC separation was performed following IMAC purification of GNC92H2scFv from Escherichia coli cell culture supernatant. The resulting HPLC effluent was then freeze-dried to afford a salt-free lyophilizate amenable to long-term storage with minimal loss in binding activity. HPLC purification also effectively removed an 80-kDa protein contaminant that co-eluted with the IMAC-purified protein. Of special importance for in vivo applications of recombinantly expressed protein therapeutics, an HPLC purification step afforded a 1000-fold reduction in lipopolysaccharide (LPS) endotoxin contamination in the final GNC92H2scFv product.
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Abstract
A chemo- and regioselective auxiliary-mediated peptide ligation has been developed that is effective under nonidealized conditions for the synthesis of proteins. This general amide bond ligation utilizes a removable auxiliary that is analogous to the role of cysteine in native chemical ligation, combining chemoselective thioester exchange with efficient regioselective intramolecular acyl transfer. Acid lability and improved ligation efficiency were introduced into the 2-mercaptobenzyl auxiliary by increasing the electron density of the aromatic ring. The 62 amino acid SH3 domain from alpha-spectrin was synthesized using the auxiliary-mediated ligation at a Lys-Gly sequence. The auxiliary was removed with TFA and scavengers from the ligated product. This methodology enables unprotected peptides to be coupled at noncysteine ligation sites expanding the scope of protein synthesis and semisynthesis.
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Abstract
Highly chemoselective amide forming ligation reactions have facilitated the synthetic access to proteins and other amide-linked bioconjugates. In order to generalize this approach, a N(alpha)-2-phenyl ethanethiol scaffold has been developed to promote S to N acyl transfer in a manner analogous to native chemical ligation with N-terminal cysteine residues. Analysis of scaffold-mediated ligation reactions in aqueous solution indicate that the ligation rate at Xaa-Gly junctions is sufficient for the synthesis of large polypeptides. In addition, it was found that the ligation rate is independent of the stereocenter in the scaffold and S- to N-acyl transfer is rate limiting. These studies indicate that the N(alpha)-2-phenyl ethanethiol scaffold is a good candidate for the development of a ligation chemistry for the formation of Xaa-Gly peptides and other unhindered amides.
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Abstract
[reaction: see text] The selective formation of an amide bond in the presence of unprotected functional groups is a challenging problem of peptide chemistry. A 2-mercaptobenzyl group tethered at the N-terminus of model peptides was observed to facilitate amide bond formation when a peptide thioester was added under mild aqueous conditions.
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Idealist thought, social policy and the rediscovery of informal care. THE BRITISH JOURNAL OF SOCIOLOGY 1999; 50:467-488. [PMID: 15259196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recent work in the history of welfare has suggested a need to reconsider the status of some conceptual frameworks within sociology and social policy studies regarding the meaning of 'social welfare' and the 'welfare state'. In this context, the present article argues in particular that the marked upswing of interest in informal care in the UK beginning in the 1970s reflected, at least in part, a reaction, itself not so far adequately understood, to some features of the work of Richard Titmuss and 'traditional social administration', work which, on examination, reveals a distinctive 'idealist' core, unsympathetic to research into familial patterns of caring. Similarities with 'classic' British idealism, broadly defined, at the end of the nineteenth and beginning of the twentieth centuries are reviewed. This idealist thought emerges too as unresponsive to informal care, even though contemporary non-idealist thought had discussed it. The article concludes that the (unacknowledged) persistence and influence of idealist modes of social thought diverted attention away from informal care; informal care was in fact not 'discovered' in the 1970s, it was rediscovered as idealist preconceptions about the nature of 'real' welfare were discarded. The sense of 'discovery' reflected prevailing and dubious historigraphical interpretations of the meaning of 'social welfare' and the status of the ('classic') 'welfare state'.
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On-resin solid-phase synthesis of asparagine N-linked glycopeptides: use of N-(2-acetoxy-4-methoxybenzyl)(AcHmb) aspartyl amide-bond protection to prevent unwanted aspartimide formation. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/p19960000175] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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The proximal pathway of metabolism of the chlorinated signal molecule differentiation-inducing factor-1 (DIF-1) in the cellular slime mould Dictyostelium. Biochem J 1995; 306 ( Pt 3):735-43. [PMID: 7702568 PMCID: PMC1136583 DOI: 10.1042/bj3060735] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Stalk cell differentiation during development of the slime mould Dictyostelium is induced by a chlorinated alkyl phenone called differentiation-inducing factor-1 (DIF-1). Inactivation of DIF-1 is likely to be a key element in the DIF-1 signalling system, and we have shown previously that this is accomplished by a dedicated metabolic pathway involving up to 12 unidentified metabolites. We report here the structure of the first four metabolites produced from DIF-1, as deduced by m.s., n.m.r. and chemical synthesis. The structures of these compounds show that the first step in metabolism is a dechlorination of the phenolic ring, producing DIF metabolite 1 (DM1). DM1 is identical with the previously known minor DIF activity, DIF-3. DIF-3 is then metabolized by three successive oxidations of its aliphatic side chain: a hydroxylation at omega-2 to produce DM2, oxidation of the hydroxy group to a ketone group to produce DM3 and a further hydroxylation at omega-1 to produce DM4, a hydroxyketone of DIF-3. We have investigated the enzymology of DIF-1 metabolism. It is already known that the first step, to produce DIF-3, is catalysed by a novel dechlorinase. The enzyme activity responsible for the first side-chain oxidation (DIF-3 hydroxylase) was detected by incubating [3H]DIF-3 with cell-free extracts and resolving the reaction products by t.l.c. DIF-3 hydroxylase has many of the properties of a cytochrome P-450. It is membrane-bound and uses NADPH as co-substrate. It is also inhibited by CO, the classic cytochrome P-450 inhibitor, and by several other cytochrome P-450 inhibitors, as well as by diphenyliodonium chloride, an inhibitor of cytochrome P-450 reductase. DIF-3 hydroxylase is highly specific for DIF-3: other closely related compounds do not compete for the activity at 100-fold molar excess, with the exception of the DIF-3 analogue lacking the chlorine atom. The Km for DIF-3 of 47 nM is consistent with this enzyme being responsible for DIF-3 metabolism in vivo. The two further oxidations necessary to produce DM4 are also performed in vitro by similar enzyme activities. One of the inhibitors of DIF-3 hydroxylase, ancymidol (IC50 67 nM) is likely to be particularly suitable for probing the function of DIF metabolism during development.
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Abstract
The six monodeoxyfluoro-myo-inositols (nFIns) have previously been synthesized as potential inhibitors of signalling pathways mediated by phosphoinositides and their derivatives. Each of the six nFIns isomers was introduced into Swiss 3T3 fibroblasts by the techniques of microinjection or scrape loading at intracellular concentrations of approx. 2-4 mM. Of the six nFIns analogues, only 3FIns and 5FIns inhibited the serum-stimulated proliferation of 3T3 fibroblasts assayed by cell counting. Proliferation was inhibited to a similar extent by 3FIns or 5FIns, irrespective of which technique was used to introduce the nFIns analogues into the cells. Proliferation of cells 35 h after serum stimulation (i.e. when the first cell cycle was completed in control cells) was inhibited by approx. 50% by both 3FIns and 5FIns, and entry into S phase in the first cell cycle was inhibited to the same extent. This indicated that the nFIns analogues were inhibiting proliferation in the G1 phase of the cell cycle. Proliferation during the second cell cycle (35-60 h after stimulation) was inhibited by 75-85%. The inhibitory nFIns analogues were not toxic to the cells, nor did they affect the cellular ATP/ADP ratio. The effectiveness of the nFIns analogues in inhibiting proliferation was directly correlated with their ability to be incorporated into phosphatidylinositol analogues, suggesting that they may act by modulating phosphoinositide signalling pathways or other functions essential for DNA synthesis.
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The uptake of 3H-labelled monodeoxyfluoro-myo-inositols into thymocytes and their incorporation into phospholipid in permeabilized cells. Biochem J 1993; 291 ( Pt 2):553-60. [PMID: 8387272 PMCID: PMC1132560 DOI: 10.1042/bj2910553] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Monodeoxyfluoro-myo-inositols were applied to electropermeabilized and intact thymocyte preparations to study their metabolism and uptake in order to investigate their suitability as potential inhibitors of phosphoinositide-mediated cellular responses. Only three of the monodeoxyfluoro-myo-inositols were incorporated into the phospholipids of thymocytes: 1D-3-deoxy-3-fluoro-myo-inositol, 5-deoxy-5-fluoro-myo-inositol and 1D-6-deoxy-6-fluoro-myo-inositol, all of which were weaker substrates for phosphatidylinositol synthase than was myo-inositol. The 3-, 5- and 6-fluoro analogues also behaved as competitive inhibitors, with K1 values of 350 +/- 5 microM, 350 +/- 5 microM and 2.9 +/- 2 mM respectively, compared with a Km for myo-inositol of 31 +/- 4 microM. When incubated with electropermeabilized thymocyte preparations, these three analogues of myo-inositol all formed phospholipids with chromatographic properties which corresponded to those of substituted phosphatidylinositol and phosphatidylinositol monophosphate. The uptake of myo-inositol and of the monodeoxyfluoro-myo-inositols into intact thymocytes was studied by a dual-label technique. All the monodeoxyfluoro-myo-inositols were taken up to some extent, but only 2-deoxy-2-fluoro-myo-inositol and 1D-3-deoxy-3-fluoro-myo-inositol were actively concentrated. The monodeoxyfluoro-myo-inositols were also assayed for their ability to inhibit the uptake of myo-inositol into cells. Both 2-deoxy-2-fluoro-myo-inositol and 1D-3-deoxy-3-fluoro-myo-inositol were effective inhibitors of myo-inositol uptake. Furthermore, 1D-1-deoxy-1-fluoro-myo-inositol, which was not taken up actively, was an effective inhibitor of myo-inositol uptake. The three effective inhibitors all showed Ki values of approximately 150 microM, close to the apparent Km for inositol uptake of 180 microM, and the 4-, 5- and 6-fluoro analogues had Ki values in excess of 10 mM.
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Normal adolescent males: the high school and college years. JOURNAL OF THE AMERICAN COLLEGE HEALTH ASSOCIATION 1974; 22:209-15. [PMID: 4815381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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