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Adebomi V, Sriram M, Streety X, Raj M. Metal-Free Selective Modification of Secondary Amides: Application in Late-Stage Diversification of Peptides. Org Lett 2021; 23:6189-6193. [PMID: 34251828 DOI: 10.1021/acs.orglett.1c01622] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here we solve a long-standing challenge of the site-selective modification of secondary amides and present a simple two-step, metal-free approach to selectively modify a particular secondary amide in molecules containing multiple primary and secondary amides. Density functional theory (DFT) provides insight into the activation of C-N bonds. This study encompasses distinct chemical advances for late-stage modification of peptides thus harnessing the amides for the incorporation of various functional groups into natural and synthetic molecules.
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Abel S, Renz P, Colonias A, Raj M, Wegner R. PD-0847 Dose escalation in locally advanced NSCLC: comparing outcomes in adenocarcinoma and squamous cell carcinoma. Radiother Oncol 2021. [DOI: 10.1016/s0167-8140(21)07126-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Nwajiobi O, Mahesh S, Streety X, Raj M. Selective Triazenation Reaction (STaR) of Secondary Amines for Tagging Monomethyl Lysine Post-Translational Modifications. Angew Chem Int Ed Engl 2021; 60:7344-7352. [PMID: 33354813 DOI: 10.1002/anie.202013997] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 11/29/2020] [Indexed: 11/09/2022]
Abstract
Lysine monomethylation (Kme) is an impactful post-translational modification (PTM) responsible for regulating biological processes and implicated in diseases, thus there is great interest in identifying these methylation marks globally. However, the progress in this area has been challenging because the addition of a small methyl group on lysine leads to negligible change in the bulk, charge, and hydrophobicity. Herein, we report an empowering chemical technology selective triazenation reaction, which we term "STaR", of secondary amines using arene diazonium salts to achieve highly selective, rapid, and robust tagging of Kme peptides from a complex mixture under biocompatible conditions. Although the resulting triazene-linkage with Kme is stable, we highlight the efficient decoupling of the triazene-conjugate to afford unmodified starting components under mild conditions when desired. Our work establishes a unique chemoselective, traceless bioconjugation strategy for the selective enrichment of Kme PTMs.
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Tang KC, Raj M. One‐Step Azolation Strategy for Site‐ and Chemo‐Selective Labeling of Proteins with Mass‐Sensitive Probes. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202007608] [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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Tang KC, Raj M. One‐Step Azolation Strategy for Site‐ and Chemo‐Selective Labeling of Proteins with Mass‐Sensitive Probes. Angew Chem Int Ed Engl 2020; 60:1797-1805. [PMID: 33047860 PMCID: PMC10111340 DOI: 10.1002/anie.202007608] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Indexed: 11/09/2022]
Abstract
The chemical modification of proteins in a site-selective manner leads to many advances in various scientific fields. The major challenges with conventional N-terminal bioconjugation techniques are the lack of universal sequence compatibility and poor mass-detection sensitivity of the resulting bioconjugates. This approach efficiently analyzes proteolytic fragments and native proteins in a complex mixture. Multiple chemical steps are usually required for the site-selective synthesis of bioconjugates with enhanced mass-detection sensitivity. We present a single-step, versatile strategy for the selective modification of protein N-termini with mass boosters. The chemical tag enhances the peptide detection by multiple orders thus leading to the unambiguous analysis of the resulting bioconjugates. We demonstrate that tagging proteolytic fragments with mass sensitivity probes in a complex mixture improves the detection of resulting bioconjugates.
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Raj M, Wills RD, Adebomi VT. Peptide Cyclization at High Concentration. Synlett 2020. [DOI: 10.1055/s-0040-1707165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The emergence of cyclic peptides as pharmaceuticals has led to an eruption of new methodologies for macrocyclization. However, the cyclization of peptides at high concentrations presents a challenge due to the production of side products like dimers and oligomers. This factor is more pronounced with the cyclization of peptides composed of fewer than seven amino acids, thus has created a need for a new synthetic strategy. Herein, we will elucidate a new chemoselective method termed ‘CyClick’ that works in an exclusively intramolecular fashion preventing the formation of commonly occurring side products such as dimers and oligomers, even at relatively high concentration.1 Introduction2 Known Methodologies3 Novel CyClick Chemistry4 Conclusion and Outlook
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Wills R, Adebomi V, Raj M. Site-Selective Peptide Macrocyclization. Chembiochem 2020; 22:52-62. [PMID: 32794268 DOI: 10.1002/cbic.202000398] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 08/11/2020] [Indexed: 12/11/2022]
Abstract
Cyclized peptides have seen a rise in popularity in the pharmaceutical industry as drug molecules. As such, new macrocyclization methodologies have become abundant in the last several decades. However, efficient methods of cyclization without the formation of side products remain a great challenge. Herein, we review cyclization approaches that focus on site-selective chemistry. Site selectivity in macrocyclization decreases the generation of side products, leading to a greater yield of the desired peptide macrocycles. We will also take an in-depth look at the new exclusively intramolecular N-terminal site-selective CyClick strategy for the synthesis of cyclic peptides. The CyClick method uses imine formation between an aldehyde and the N terminus. The imine is then trapped by a nucleophilic attack from the second amidic nitrogen in an irreversible site-selective fashion.
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Mahesh S, Adebomi V, Muneeswaran ZP, Raj M. Bioinspired Nitroalkylation for Selective Protein Modification and Peptide Stapling. Angew Chem Int Ed Engl 2020; 59:2793-2801. [DOI: 10.1002/anie.201908593] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Indexed: 01/05/2023]
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Mahesh S, Adebomi V, Muneeswaran ZP, Raj M. Bioinspired Nitroalkylation for Selective Protein Modification and Peptide Stapling. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201908593] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Adebomi V, Cohen RD, Wills R, Chavers HAH, Martin GE, Raj M. CyClick Chemistry for the Synthesis of Cyclic Peptides. Angew Chem Int Ed Engl 2019; 58:19073-19080. [DOI: 10.1002/anie.201911900] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Indexed: 01/07/2023]
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Sim YE, Nwajiobi O, Mahesh S, Cohen RD, Reibarkh MY, Raj M. Secondary amine selective Petasis (SASP) bioconjugation. Chem Sci 2019; 11:53-61. [PMID: 32110356 PMCID: PMC7012053 DOI: 10.1039/c9sc04697f] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 10/29/2019] [Indexed: 11/21/2022] Open
Abstract
Secondary amine selective Petasis (SASP) bioconjugation for the selective labeling of peptides and proteins with N-terminal secondary amines.
Selective modification of proteins enables synthesis of antibody-drug conjugates, cellular drug delivery and construction of new materials. Many groups have developed methods for selective N-terminal modification without affecting the side chain of lysine by judicious pH control. This is due to lower basicity of the N-terminus relative to lysine side chains. But none of the methods are capable of selective modification of secondary amines or N-terminal proline, which has similar basicity as lysine. Here, we report a secondary amine selective Petasis (SASP) reaction for selective bioconjugation at N-terminal proline. We exploited the ability of secondary amines to form highly electrophilic iminium ions with aldehydes, which rapidly reacted with nucleophilic organoboronates, resulting in robust labeling of N-terminal proline under biocompatible conditions. This is the first time the Petasis reaction has been utilized for selective modification of secondary amines on completely unprotected peptides and proteins under physiological conditions. Peptide screening results showed that the reaction is highly selective for N-terminal proline. There are no other chemical methods reported in literature that are selective for N-terminal proline in both peptides and proteins. This is a multicomponent reaction leading to the synthesis of doubly functionalized bioconjugates in one step that can be difficult to achieve using other methods. The key advantage of the SASP reaction includes its high chemoselective and stereoselective (>99% de) nature, and it affords dual labeled proteins in one pot. The broad utility of this bioconjugation is highlighted for a variety of peptides and proteins, including aldolase and creatine kinase.
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Adebomi V, Cohen RD, Wills R, Chavers HAH, Martin GE, Raj M. CyClick Chemistry for the Synthesis of Cyclic Peptides. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201911900] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Mahesh S, Tang KC, Raj M. Amide Bond Activation of Biological Molecules. Molecules 2018; 23:E2615. [PMID: 30322008 PMCID: PMC6222841 DOI: 10.3390/molecules23102615] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 12/02/2022] Open
Abstract
Amide bonds are the most prevalent structures found in organic molecules and various biomolecules such as peptides, proteins, DNA, and RNA. The unique feature of amide bonds is their ability to form resonating structures, thus, they are highly stable and adopt particular three-dimensional structures, which, in turn, are responsible for their functions. The main focus of this review article is to report the methodologies for the activation of the unactivated amide bonds present in biomolecules, which includes the enzymatic approach, metal complexes, and non-metal based methods. This article also discusses some of the applications of amide bond activation approaches in the sequencing of proteins and the synthesis of peptide acids, esters, amides, and thioesters.
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Zong C, Cheung-Lee WL, Elashal HE, Raj M, Link AJ. Albusnodin: an acetylated lasso peptide from Streptomyces albus. Chem Commun (Camb) 2018; 54:1339-1342. [PMID: 29350227 DOI: 10.1039/c7cc08620b] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We describe a lasso peptide, albusnodin, that is post-translationally modified with an acetyl group, the first example of a lasso peptide with this modification. Using heterologous expression, we further show that the acetyltransferase colocalized with the albusnodin gene cluster is required for the biosynthesis of this lasso peptide. This type of lasso peptide is widespread in Actinobacteria with 44 examples found in currently sequenced genomes.
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Howard TS, Cohen RD, Nwajiobi O, Muneeswaran ZP, Sim YE, Lahankar NN, Yeh JTH, Raj M. Amino-Acid-Catalyzed Direct Aldol Bioconjugation. Org Lett 2018; 20:5344-5347. [PMID: 30125118 PMCID: PMC7751349 DOI: 10.1021/acs.orglett.8b02265] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A site-specific bioconjugation was developed based on direct aldol coupling using amino-acid-derived organocatalysts. The functionalization exhibits fast kinetics and occurs under mild, biocompatible conditions (viz., aqueous media, moderate temperature, and neutral pH). The resulting bioconjugates were found to be stable toward abundant aldolase enzymes, as well as acidic and basic pH. The methodology was demonstrated through conjugation of a variety of small molecules, dyes, and peptides to proteins, including a single-domain antibody, which was then used for cellular imaging.
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Raj M, Elashal HE, Elashal HE, Cohen RD. Cyclic and Lasso Peptides: Sequence Determination, Topology Analysis, and Rotaxane Formation. Angew Chem Int Ed Engl 2018; 57:6150-6154. [PMID: 29645322 PMCID: PMC6080247 DOI: 10.1002/anie.201801299] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Indexed: 01/07/2023]
Abstract
A broadly applicable chemical cleavage methodology to facilitate MS/MS sequencing was developed for macrocyclic and lasso peptides, which hold promise as exciting new therapeutics. Existing methods such as Edman degradation, CNBr cleavage, and enzymatic digestion are either limited in scope or completely fail in cleavage of constrained nonribosomal peptides. Importantly, the new method was utilized for synthesizing a unique peptide-based rotaxane (both cyclic and threaded) from the lasso peptide, benenodin-1 ΔC5.
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Elashal HE, Cohen RD, Elashal HE, Zong C, Link AJ, Raj M. Cyclic and Lasso Peptides: Sequence Determination, Topology Analysis, and Rotaxane Formation. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201801299] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Elashal HE, Cohen RD, Elashal HE, Raj M. Oxazolidinone-Mediated Sequence Determination of One-Bead One-Compound Cyclic Peptide Libraries. Org Lett 2018; 20:2374-2377. [PMID: 29617143 DOI: 10.1021/acs.orglett.8b00717] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel one-bead one-compound (OBOC) dual ring-opening/cleavage approach for cyclic peptide sequencing was developed. The method selectively modifies serine, cysteine, threonine, and/or glutamic acid to an oxazolidinone-derived moiety, thereby increasing the susceptibility of the modified peptide backbone toward hydrolysis. The resulting linear peptide was then sequenced in 1 min by tandem mass spectrometry on a quadrupole time-of-flight instrument incorporating two-dimensional liquid chromatography and ion mobility spectrometry separation. To evaluate this approach, a library of cyclic peptides was successfully sequenced with 98% overall accuracy, demonstrating its robustness and broad substrate scope.
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Nwajiobi O, Raj M. SYNTHESIS OF FUNCTIONALIZED MACROCYCLIC PEPTIDES. Front Chem 2018. [DOI: 10.3389/conf.fchem.2018.01.00051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Hasan S, Jani P, Monga D, McCormick J, Kirichenko A, Raj M. Short-Term Extended Capecitabine Following Neoadjuvant Concurrent Chemoradiation for Rectal Cancer May Improve Pathologic Complete Response Rate. Int J Radiat Oncol Biol Phys 2017. [DOI: 10.1016/j.ijrobp.2017.06.963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Wu H, Handoko, Raj M, Arora PS. Iterative Design of a Biomimetic Catalyst for Amino Acid Thioester Condensation. Org Lett 2017; 19:5122-5125. [DOI: 10.1021/acs.orglett.7b02412] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sidharthan N, Sudevan R, Narayana Pillai V, Mathew S, Raj M, Viswam D, Joseph C, Sudhakar A. Low-dose prophylaxis for children with haemophilia in a resource-limited setting in south India-A clinical audit report. Haemophilia 2017; 23:e382-e384. [DOI: 10.1111/hae.13272] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2017] [Indexed: 11/28/2022]
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More S, Bicout D, Bøtner A, Butterworth A, Calistri P, Depner K, Edwards S, Garin-Bastuji B, Good M, Gortázar Schmidt C, Michel V, Miranda MA, Saxmose Nielsen S, Raj M, Sihvonen L, Spoolder H, Thulke HH, Velarde A, Willeberg P, Winckler C, Adlhoch C, Baldinelli F, Breed A, Brouwer A, Guillemain M, Harder T, Monne I, Roberts H, Cortinas Abrahantes J, Mosbach-Schulz O, Verdonck F, Morgado J, Stegeman A. Urgent request on avian influenza. EFSA J 2017; 15:e04687. [PMID: 32625275 PMCID: PMC7009852 DOI: 10.2903/j.efsa.2016.4687] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Highly pathogenic avian influenza (HPAI) H5N8 is currently causing an epizootic in Europe, infecting many poultry holdings as well as captive and wild bird species in more than 10 countries. Given the clear clinical manifestation, passive surveillance is considered the most effective means of detecting infected wild and domestic birds. Testing samples from new species and non‐previously reported areas is key to determine the geographic spread of HPAIV H5N8 2016 in wild birds. Testing limited numbers of dead wild birds in previously reported areas is useful when it is relevant to know whether the virus is still present in the area or not, e.g. before restrictive measures in poultry are to be lifted. To prevent introduction of HPAIV from wild birds into poultry, strict biosecurity implemented and maintained by the poultry farmers is the most important measure. Providing holding‐specific biosecurity guidance is strongly recommended as it is expected to have a high impact on the achieved biosecurity level of the holding. This is preferably done during peace time to increase preparedness for future outbreaks. The location and size of control and in particular monitoring areas for poultry associated with positive wild bird findings are best based on knowledge of the wider habitat and flight distance of the affected wild bird species. It is recommended to increase awareness among poultry farmers in these established areas in order to enhance passive surveillance and to implement enhanced biosecurity measures including poultry confinement. There is no scientific evidence suggesting a different effectiveness of the protection measures on the introduction into poultry holdings and subsequent spread of HPAIV when applied to H5N8, H5N1 or other notifiable HPAI viruses. This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2016.EN-1142/full
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Raj M, Choi SW, Platt J. A qualitative exploration of the informed consent process in hematopoietic cell transplantation clinical research and opportunities for improvement. Bone Marrow Transplant 2016; 52:292-298. [PMID: 27748736 DOI: 10.1038/bmt.2016.252] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 07/29/2016] [Accepted: 08/06/2016] [Indexed: 11/09/2022]
Abstract
Informed consent (IC) struggles to meet the ethical principles it strives to embody in the context of hematopoietic cell transplantation (HCT). Patients often participate in multiple clinical trials making it difficult to effectively inform the participants and fulfill complex regulations. The recent Notice of Proposed Rule Making would make major changes to federal requirements, providing a timely opportunity to evaluate existing practice. Twenty health care professionals within a Midwest Academic Medical Center involved in obtaining IC in the HCT clinic or involved in patient care during or after the IC process were interviewed to understand: (1) how they approached the IC process; (2) how they described a 'successful' IC process; and (3) opportunities for innovation. Narrative and discourse analyses of interviews indicate that providers understand IC to be a collaborative process requiring engagement and participation of providers, patients and caregivers. 'Markers of success' were identified including cognitive, affective and procedural markers focusing on patient understanding and comfort with the decision to participate. Opportunities for innovating the process included use of decision aids and tablet-based technology, and better use of patient portals. Our findings suggest specific interventions for the IC process that could support the process of consent for providers, patients and caregivers.
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Elashal HE, Sim YE, Raj M. Serine promoted synthesis of peptide thioester-precursor on solid support for native chemical ligation. Chem Sci 2016; 8:117-123. [PMID: 28451155 PMCID: PMC5308276 DOI: 10.1039/c6sc02162j] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 07/28/2016] [Indexed: 01/03/2023] Open
Abstract
Fmoc solid phase peptide synthesis of peptide thioesters by displacement of the cyclic urethane moiety obtained by the selective activation of C-terminal serine.
Fmoc solid phase peptide synthesis of thioesters for the chemical synthesis of proteins via native chemical ligation is a challenge. We have developed a versatile approach for direct synthesis of peptide thioesters from a solid support utilizing Fmoc chemistry. Peptide thioester synthesis is performed by the formation of a cyclic urethane moiety via a selective reaction of the backbone amide chain with the side group of serine. The activated cyclic urethane moiety undergoes displacement by a thiol to generate the thioester directly from the solid support. Importantly, the method activates the serine residue for the synthesis of peptide thioesters; thus it is fully automated and free of the types of resins, linkers, handles, and unnatural amino acids typically needed for the synthesis of peptide thioesters using Fmoc chemistry. The resulting thioester is free of epimerization and is successfully applied for the synthesis of longer peptides using NCL.
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