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Puente EG, Sivasankaran RP, Vinciguerra D, Yang J, Lower HAC, Hevener AL, Maynard HD. Uniform trehalose nanogels for glucagon stabilization. RSC APPLIED POLYMERS 2024; 2:473-482. [PMID: 38800515 PMCID: PMC11114568 DOI: 10.1039/d3lp00226h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 02/14/2024] [Indexed: 05/29/2024]
Abstract
Glucagon is a peptide hormone that acts via receptor-mediated signaling predominantly in the liver to raise glucose levels by hepatic glycogen breakdown or conversion of noncarbohydrate, 3 carbon precursors to glucose by gluconeogenesis. Glucagon is administered to reverse severe hypoglycemia, a clinical complication associated with type 1 diabetes. However, due to low stability and solubility at neutral pH, there are limitations in the current formulations of glucagon. Trehalose methacrylate-based nanoparticles were utilized as the stabilizing and solubilizing moiety in the system reported herein. Glucagon was site-selectively modified to contain a cysteine at amino acid number 24 to covalently attach to the methacrylate-based polymer containing pyridyl disulfide side chains. PEG2000 dithiol was employed as the crosslinker to form uniform nanoparticles. Glucagon nanogels were monitored in Dulbecco's phosphate-buffered saline (DPBS) pH 7.4 at various temperatures to determine its long-term stability in solution. Glucagon nanogels were stable up to at least 5 months by size uniformity when stored at -20 °C and 4 °C, up to 5 days at 25 °C, and less than 12 hours at 37 °C. When glucagon stability was studied by either HPLC or thioflavin T assays, the glucagon was intact for at least 5 months at -20 °C and 4 °C within the nanoparticles at -20 °C and 4 °C and up to 2 days at 25 °C. Additionally, the glucagon nanogels were studied for toxicity and efficacy using various assays in vitro. The findings indicate that the nanogels were nontoxic to fibroblast cells and nonhemolytic to red blood cells. The glucagon in the nanogels was as active as glucagon alone. These results demonstrate the utility of trehalose nanogels towards a glucagon formulation with improved stability and solubility in aqueous solutions, particularly useful for storage at cold temperatures.
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Affiliation(s)
- Ellie G Puente
- Department of Chemistry and Biochemistry, University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles California 90095-1569 USA
- California Nanosystems Institute, University of California, Los Angeles 570 Westwood Plaza Los Angeles California 90095-1569 USA
| | - Rajalakshmi P Sivasankaran
- Department of Chemistry and Biochemistry, University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles California 90095-1569 USA
- California Nanosystems Institute, University of California, Los Angeles 570 Westwood Plaza Los Angeles California 90095-1569 USA
| | - Daniele Vinciguerra
- Department of Chemistry and Biochemistry, University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles California 90095-1569 USA
- California Nanosystems Institute, University of California, Los Angeles 570 Westwood Plaza Los Angeles California 90095-1569 USA
| | - Jane Yang
- Department of Chemistry and Biochemistry, University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles California 90095-1569 USA
- California Nanosystems Institute, University of California, Los Angeles 570 Westwood Plaza Los Angeles California 90095-1569 USA
| | - Haillie-Ann C Lower
- Department of Chemistry and Biochemistry, University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles California 90095-1569 USA
- California Nanosystems Institute, University of California, Los Angeles 570 Westwood Plaza Los Angeles California 90095-1569 USA
| | - Andrea L Hevener
- Division of Endocrinology, Diabetes, and Hypertension, Department of Medicine, David Geffen School of Medicine University of California, Los Angeles Los Angeles CA USA
- Department of Medicine and VA Greater Los Angeles Healthcare System GRECC Los Angeles CA 90073 USA
| | - Heather D Maynard
- Department of Chemistry and Biochemistry, University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles California 90095-1569 USA
- California Nanosystems Institute, University of California, Los Angeles 570 Westwood Plaza Los Angeles California 90095-1569 USA
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2
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Liu M, Zhao P, Uddin MH, Li W, Lin F, Chandrashekar C, Nishiuchi Y, Kajihara Y, Forbes BE, Wootten D, Wade JD, Hossain MA. Chemical Synthesis and Characterization of a Nonfibrillating Glycoglucagon. Bioconjug Chem 2021; 32:2148-2153. [PMID: 34494823 DOI: 10.1021/acs.bioconjchem.1c00419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The current commercially available glucagon formulations for the treatment of severe hypoglycemia must be reconstituted immediately prior to use, owing to the susceptibility of glucagon to fibrillation and aggregation in an aqueous solution. This results in the inconvenience of handling, misuse, and wastage of this drug. To address these issues, we synthesized a glycosylated glucagon analogue in which the 25th residue (Trp) was replaced with a cysteine (Cys) and a Br-disialyloligosaccharide was conjugated at the Cys thiol moiety. The resulting analogue, glycoglucagon, is a highly potent full agonist at the glucagon receptor. Importantly, glycoglucagon exhibits markedly reduced propensity for fibrillation and enhanced thermal and metabolic stability. This novel analogue is thus a valuable lead for producing stable liquid glucagon formulations that will improve patient compliance and minimize wastage.
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Affiliation(s)
| | - Peishen Zhao
- Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Md Hemayet Uddin
- Melbourne Centre for Nanofabrication, Melbourne, Victoria 3168, Australia
| | | | | | | | - Yuji Nishiuchi
- GlyTech, Inc., 134 Chudoji Minamimachi, Kyoto, 600-8813, Japan.,Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8579, Japan
| | - Yasuhiro Kajihara
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 Japan
| | - Briony E Forbes
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia 5042, Australia
| | - Denise Wootten
- Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria 3052, Australia
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3
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Chandrashekar C, Hossain MA, Wade JD. Chemical Glycosylation and Its Application to Glucose Homeostasis-Regulating Peptides. Front Chem 2021; 9:650025. [PMID: 33912539 PMCID: PMC8072350 DOI: 10.3389/fchem.2021.650025] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
Peptides and proteins are attractive targets for therapeutic drug development due to their exquisite target specificity and low toxicity profiles. However, their complex structures give rise to several challenges including solubility, stability, aggregation, low bioavailability, and poor pharmacokinetics. Numerous chemical strategies to address these have been developed including the introduction of several natural and non-natural modifications such as glycosylation, lipidation, cyclization and PEGylation. Glycosylation is considered to be one of the most useful modifications as it is known to contribute to increasing the stability, to improve solubility, and increase the circulating half-lifves of these biomolecules. However, cellular glycosylation is a highly complex process that generally results in heterogenous glycan structures which confounds quality control and chemical and biological assays. For this reason, much effort has been expended on the development of chemical methods, including by solid phase peptide synthesis or chemoenzymatic processes, to enable the acquisition of homogenous glycopeptides to greatly expand possibilities in drug development. In this mini-review, we highlight the importance of such chemical glycosylation methods for improving the biophysical properties of naturally non-glycosylated peptides as applied to the therapeutically essential insulin and related peptides that are used in the treatment of diabetes.
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Affiliation(s)
- Chaitra Chandrashekar
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia
| | - Mohammed Akhter Hossain
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia
| | - John D Wade
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia.,School of Chemistry, University of Melbourne, Melbourne, VIC, Australia
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4
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Egbu R, van der Walle CF, Brocchini S, Williams GR. Inhibiting the fibrillation of a GLP-1-like peptide. Int J Pharm 2020; 574:118923. [PMID: 31812799 DOI: 10.1016/j.ijpharm.2019.118923] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/28/2019] [Accepted: 11/30/2019] [Indexed: 11/30/2022]
Abstract
Aggregation, including the formation of fibrils, poses significant challenges for the development of therapeutic peptides. To prepare stable peptide formulations, some understanding of the mechanisms underpinning the fibrillation process is required. A thioflavin T fluorescence assay was first used to determine the fibrillation profile of a GLP-1-like peptide (G48) at conditions being considered to formulate the peptide. G48 concentrations ranged from 0 to 600 µM and three pH values (pH 3.7, 7.4 and 8.5) were evaluated. Kinetic data demonstrate that G48 displays a pH-dependent aggregation profile. At pH 3.7, which is below the isoelectric point of G48 (pI ~ 5), kinetics representative of amorphous aggregates forming via a nucleation-independent mechanism were seen. At pH 7.4 and 8.5 (pH > pI) typical nucleation-dependent aggregation kinetics were observed. The weight concentration of β-sheet rich aggregates (FLmax) correlated inversely with net charge, so lower FLmax values were observed at pH 3.7 and 8.5 than at pH 7.4. Incorporation of a non-ionic surfactant (polysorbate 80) into the peptide solution suppressed the fibrillation of G48 at all pH values and maintained the native peptide conformation, whereas a phenolic co-formulant (ferulic acid) had minimal effects on fibril growth. Peptide fibrillation, which can occur within a range of formulation concentrations and pH values, can hence be inhibited by the judicious use of excipients.
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Affiliation(s)
- Raphael Egbu
- UCL School of Pharmacy, University College London, London WC1N 1AX, UK
| | | | - Steve Brocchini
- UCL School of Pharmacy, University College London, London WC1N 1AX, UK
| | - Gareth R Williams
- UCL School of Pharmacy, University College London, London WC1N 1AX, UK.
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5
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Rashid MA, Elgied AA, Alhamhoom Y, Chan E, Rintoul L, Allahham A, Islam N. Excipient Interactions in Glucagon Dry Powder Inhaler Formulation for Pulmonary Delivery. Pharmaceutics 2019; 11:E207. [PMID: 31052466 PMCID: PMC6571834 DOI: 10.3390/pharmaceutics11050207] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/11/2019] [Accepted: 04/29/2019] [Indexed: 11/23/2022] Open
Abstract
PURPOSE This study describes the development and characterization of glucagon dry powder inhaler (DPI) formulation for pulmonary delivery. Lactose monohydrate, as a carrier, and L-leucine and magnesium stearate (MgSt) were used as dispersibility enhancers for this formulation. METHODS Using Fourier-transform infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), and Raman confocal microscopy, the interactions between glucagon and all excipients were characterized. The fine particle fractions (FPFs) of glucagon in different formulations were determined by a twin stage impinger (TSI) using a 2.5% glucagon mixture, and the glucagon concentration was measured by a validated LC-MS/MS method. RESULTS The FPF of the glucagon was 6.4%, which increased six-fold from the formulations with excipients. The highest FPF (36%) was observed for the formulation containing MgSt and large carrier lactose. The FTIR, Raman, and DSC data showed remarkable physical interactions of glucagon with leucine and a minor interaction with lactose; however, there were no interactions with MgSt alone or mixed with lactose. CONCLUSION Due to the interaction between L-leucine and glucagon, leucine was not a suitable excipient for glucagon formulation. In contrast, the use of lactose and MgSt could be considered to prepare an efficient DPI formulation for the pulmonary delivery of glucagon.
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Affiliation(s)
- Md Abdur Rashid
- Department of Pharmaceutics, School of Pharmacy, King Khalid University, Abha, Aseer 62529, Saudi Arabia.
| | - Amged Awad Elgied
- Department of Pharmaceutics, School of Pharmacy, King Khalid University, Abha, Aseer 62529, Saudi Arabia.
| | - Yahya Alhamhoom
- Department of Pharmaceutics, School of Pharmacy, King Khalid University, Abha, Aseer 62529, Saudi Arabia.
| | - Enoch Chan
- Pharmacy Discipline, School of Clinical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4000d, Australia.
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4000d, Australia.
| | - Llew Rintoul
- School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Brisbane, QLD 4000d, Australia.
| | - Ayman Allahham
- Pharmacy Program, School of Health and Biomedical Sciences, College of Science, Engineering & Health, RMIT University, Bundoora, VIC 308, Australia.
| | - Nazrul Islam
- Pharmacy Discipline, School of Clinical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD 4000d, Australia.
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4000d, Australia.
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6
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Li B, Wu Y, Zhang W, Zhang S, Shao N, Zhang W, Zhang L, Fei J, Dai Y, Liu R. Efficient synthesis of amino acid polymers for protein stabilization. Biomater Sci 2019; 7:3675-3682. [DOI: 10.1039/c9bm00484j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Poly-l-glutamate exerts substantial protein stabilization during lyophilization by preventing protein aggregation.
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7
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Gerislioglu S, Adams SR, Wesdemiotis C. Characterization of singly and multiply PEGylated insulin isomers by reversed-phase ultra-performance liquid chromatography interfaced with ion mobility mass spectrometry. Anal Chim Acta 2017; 1004:58-66. [PMID: 29329709 DOI: 10.1016/j.aca.2017.12.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/27/2017] [Accepted: 12/03/2017] [Indexed: 10/18/2022]
Abstract
Conjugation of poly(ethylene glycol) (PEG) to protein drugs (PEGylation) is increasingly utilized in the biotherapeutics field because it improves significantly the drugs' circulatory half-life, solubility, and shelf-life. The activity of a PEGylated drug depends on the number, size, and location of the attached PEG chain(s). This study introduces a 2D separation approach, including reversed-phase ultra-performance liquid chromatography (RP-UPLC) and ion mobility mass spectrometry (IM-MS), in order to determine the structural properties of the conjugates, as demonstrated for a PEGylated insulin sample that was prepared by random amine PEGylation. The UPLC dimension allowed separation based on polarity. Electrospray ionization (ESI) of the eluates followed by in-source dissociation (ISD) truncated the PEG chains and created insulin fragments that provided site-specific information based on whether they contained a marker at the potential conjugation sites. Separation of the latter fragments by size and charge in the orthogonal IM dimension (pseudo-4D UPLC-ISD-IM-MS approach) enabled clear detection and identification of the positional isomers formed upon PEGylation. The results showed a highly heterogeneous mixture of singly and multiply conjugated isomers plus unconjugated material. PEGylation was observed on all three possible attachment sites (ε-NH2 of LysB29, A- and B-chain N-termini). Each PEGylation site was validated by analysis of the same product after disulfide bond cleavage, so that the PEGylated A- and B- chain could be individually characterized with the same pseudo-4D UPLC-ISD-IM-MS method.
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Affiliation(s)
- Selim Gerislioglu
- Department of Chemistry, The University of Akron, Akron, OH 44325, USA
| | - Scott R Adams
- Department of Chemistry, The University of Akron, Akron, OH 44325, USA
| | - Chrys Wesdemiotis
- Department of Chemistry, The University of Akron, Akron, OH 44325, USA.
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8
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Higashiyama T, Umekawa M, Nagao M, Katoh T, Ashida H, Yamamoto K. Chemo-enzymatic synthesis of the glucagon containing N-linked oligosaccharide and its characterization. Carbohydr Res 2017; 455:92-96. [PMID: 29175660 DOI: 10.1016/j.carres.2017.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 11/08/2017] [Accepted: 11/11/2017] [Indexed: 12/18/2022]
Abstract
The chemo-enzymatic synthesis of an artificially N-glycosylated derivative of glucagon, a peptide hormone that regulates the blood sugar level, is described. We synthesized the glycosylated glucagon by chemical synthesis of an N-acetylglucosaminyl peptide and enzymatic transfer of an oligosaccharide using the transglycosylation activity of the glycosynthase-like mutant of Mucor hiemalis endo-β-N-acetylglucosaminidase (Endo-M) and sialo-oligosaccharide oxazoline as a donor substrate. The sialo-oligosaccharide-attached glucagon synthesized showed high resistance against protease degradation and stimulated the release of glucose from mouse hepatocytes when added to cells. The synthetic glucagon showed slightly higher activity than native glucagon and has potential as a therapeutic agent for treating diabetic patients.
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Affiliation(s)
- Takayuki Higashiyama
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
| | - Midori Umekawa
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
| | - Masaya Nagao
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan
| | - Toshihiko Katoh
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan; Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoich, Ishikawa, 921-8836, Japan
| | - Hisashi Ashida
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan; Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Wakayama, 649-6493, Japan
| | - Kenji Yamamoto
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan; Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoich, Ishikawa, 921-8836, Japan.
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9
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Turecek PL, Bossard MJ, Schoetens F, Ivens IA. PEGylation of Biopharmaceuticals: A Review of Chemistry and Nonclinical Safety Information of Approved Drugs. J Pharm Sci 2016; 105:460-475. [PMID: 26869412 DOI: 10.1016/j.xphs.2015.11.015] [Citation(s) in RCA: 456] [Impact Index Per Article: 57.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 10/01/2015] [Accepted: 10/30/2015] [Indexed: 01/01/2023]
Abstract
Modification of biopharmaceutical molecules by covalent conjugation of polyethylene glycol (PEG) molecules is known to enhance pharmacologic and pharmaceutical properties of proteins and other large molecules and has been used successfully in 12 approved drugs. Both linear and branched-chain PEG reagents with molecular sizes of up to 40 kDa have been used with a variety of different PEG derivatives with different linker chemistries. This review describes the properties of PEG itself, the history and evolution of PEGylation chemistry, and provides examples of PEGylated drugs with an established medical history. A trend toward the use of complex PEG architectures and larger PEG polymers, but with very pure and well-characterized PEG reagents is described. Nonclinical toxicology findings related to PEG in approved PEGylated biopharmaceuticals are summarized. The effect attributed to the PEG part of the molecules as observed in 5 of the 12 marketed products was cellular vacuolation seen microscopically mainly in phagocytic cells which is likely related to their biological function to absorb and remove particles and macromolecules from blood and tissues. Experience with marketed PEGylated products indicates that adverse effects in toxicology studies are usually related to the active part of the drug but not to the PEG moiety.
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Affiliation(s)
| | - Mary J Bossard
- Nektar Therapeutics, Department of Polymer Chemistry, Huntsville, Alabama 35801-5914
| | | | - Inge A Ivens
- Bayer, Toxicology, San Francisco, California 94158
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10
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Evaluation of physicochemical and stability properties of human growth hormone upon enzymatic PEGylation. J Appl Biomed 2016. [DOI: 10.1016/j.jab.2016.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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11
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D'Addio SM, Bothe JR, Neri C, Walsh PL, Zhang J, Pierson E, Mao Y, Gindy M, Leone A, Templeton AC. New and Evolving Techniques for the Characterization of Peptide Therapeutics. J Pharm Sci 2016; 105:2989-3006. [DOI: 10.1016/j.xphs.2016.06.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 06/06/2016] [Accepted: 06/17/2016] [Indexed: 01/31/2023]
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Moorthy BS, Ghomi HT, Lill MA, Topp EM. Structural transitions and interactions in the early stages of human glucagon amyloid fibrillation. Biophys J 2015; 108:937-948. [PMID: 25692598 DOI: 10.1016/j.bpj.2015.01.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 12/07/2014] [Accepted: 01/08/2015] [Indexed: 01/08/2023] Open
Abstract
A mechanistic understanding of the intermolecular interactions and structural changes during fibrillation is crucial for the design of safe and efficacious glucagon formulations. Amide hydrogen/deuterium exchange with mass spectrometric analysis was used to identify the interactions and amino acids involved in the initial stages of glucagon fibril formation at acidic pH. Kinetic measurements from intrinsic and thioflavin T fluorescence showed sigmoidal behavior. Secondary structural measurement of fibrillating glucagon using far-UV circular dichroism spectroscopy showed changes in structure from random coil → α-helix → β-sheet, with increase in α-helix content during the lag phase followed by increase in β-sheet content during the growth phase. Hydrogen/deuterium exchange with mass spectrometric analysis of fibrillating glucagon suggested that C-terminal residues 22-29 are involved in interactions during the lag phase, during which N-terminal residues 1-6 showed no changes. Molecular dynamics simulations of glucagon fragments showed C-terminal to C-terminal interactions with greater α-helix content for the 20-29 fragment, with hydrophobic and aromatic residues (Phe-22, Trp-25, Val-23, and Met-27) predominantly involved. Overall, the study shows that glucagon interactions during the early phase of fibrillation are mediated through C-terminal residues, which facilitate the formation of α-helix-rich oligomers, which further undergo structural rearrangement and elongation to form β-sheet-rich mature fibrils.
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Affiliation(s)
- Balakrishnan S Moorthy
- Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana
| | - Hamed Tabatabaei Ghomi
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Markus A Lill
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Elizabeth M Topp
- Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana.
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13
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Holm LS, Thulstrup PW, Kasimova MR, van de Weert M. Preferential Interactions and the Effect of Protein PEGylation. PLoS One 2015; 10:e0133584. [PMID: 26230338 PMCID: PMC4521882 DOI: 10.1371/journal.pone.0133584] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/29/2015] [Indexed: 01/29/2023] Open
Abstract
Background PEGylation is a strategy used by the pharmaceutical industry to prolong systemic circulation of protein drugs, whereas formulation excipients are used for stabilization of proteins during storage. Here we investigate the role of PEGylation in protein stabilization by formulation excipients that preferentially interact with the protein. Methodology/Principal Findings The model protein hen egg white lysozyme was doubly PEGylated on two lysines with 5 kDa linear PEGs (mPEG-succinimidyl valerate, MW 5000) and studied in the absence and presence of preferentially excluded sucrose and preferentially bound guanine hydrochloride. Structural characterization by far- and near-UV circular dichroism spectroscopy was supplemented by investigation of protein thermal stability with the use of differential scanning calorimetry, far and near-UV circular dichroism and fluorescence spectroscopy. It was found that PEGylated lysozyme was stabilized by the preferentially excluded excipient and destabilized by the preferentially bound excipient in a similar manner as lysozyme. However, compared to lysozyme in all cases the melting transition was lower by up to a few degrees and the calorimetric melting enthalpy was decreased to half the value for PEGylated lysozyme. The ratio between calorimetric and van’t Hoff enthalpy suggests that our PEGylated lysozyme is a dimer. Conclusion/Significance The PEGylated model protein displayed similar stability responses to the addition of preferentially active excipients. This suggests that formulation principles using preferentially interacting excipients are similar for PEGylated and non-PEGylated proteins.
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Affiliation(s)
- Louise Stenstrup Holm
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
| | - Peter W. Thulstrup
- Department of Chemistry, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Marina R. Kasimova
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marco van de Weert
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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14
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Liebner R, Meyer M, Hey T, Winter G, Besheer A. Head to head comparison of the formulation and stability of concentrated solutions of HESylated versus PEGylated anakinra. J Pharm Sci 2014; 104:515-26. [PMID: 25445200 DOI: 10.1002/jps.24253] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 10/12/2014] [Accepted: 10/17/2014] [Indexed: 12/31/2022]
Abstract
Although PEGylation of biologics is currently the gold standard for half-life extension, the technology has a number of limitations, most importantly the non-biodegradability of PEG and the extremely high viscosity at high concentrations. HESylation is a promising alternative based on coupling to the biodegradable polymer hydroxyethyl starch (HES). In this study, we are comparing HESylation with PEGylation regarding the effect on the protein's physicochemical properties, as well as on formulation at high concentrations, where protein stability and viscosity can be compromised. For this purpose, the model protein anakinra is coupled to HES or PEG by reductive amination. Results show that coupling of HES or PEG had practically no effect on the protein's secondary structure, and that it reduced protein affinity by one order of magnitude, with HESylated anakinra more affine than the PEGylated protein. The viscosity of HESylated anakinra at protein concentrations up to 75 mg/mL was approximately 40% lower than that of PEG-anakinra. Both conjugates increased the apparent melting temperature of anakinra in concentrated solutions. Finally, HESylated anakinra was superior to PEG-anakinra regarding monomer recovery after 8 weeks of storage at 40°C. These results show that HESylating anakinra offers formulation advantages compared with PEGylation, especially for concentrated protein solutions.
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Affiliation(s)
- Robert Liebner
- Department of Pharmacy, Pharmaceutical Technology & Biopharmaceutics, Ludwig-Maximillians-University Munich, Munich, 81377, Germany
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15
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Liebner R, Mathaes R, Meyer M, Hey T, Winter G, Besheer A. Protein HESylation for half-life extension: Synthesis, characterization and pharmacokinetics of HESylated anakinra. Eur J Pharm Biopharm 2014; 87:378-85. [DOI: 10.1016/j.ejpb.2014.03.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 03/13/2014] [Accepted: 03/18/2014] [Indexed: 01/07/2023]
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Huang L, Gough PC. Characterization of PEGylated biopharmaceutical products by LC/MS and LC/MS/MS. Methods Mol Biol 2012; 899:351-363. [PMID: 22735964 DOI: 10.1007/978-1-61779-921-1_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
PEGylation of peptide and proteins is an important method of improving their pharmacokinetic, pharmacodynamic, and immunological profiles, and thus enhancing their therapeutic effect. However, PEGylation of peptides and proteins creates significant challenges for detailed structural characterization, such as PEG heterogeneity, site of PEG addition, and number of attached PEG moieties. Here, we present two methodologies for the structural characterization of PEGylated peptides and proteins. LC/MS methodology utilizing post-column addition of amines was developed to obtain accurate masses of PEGylated peptides and proteins, which can be used to assign the structures and number of attached PEGs. The PEGylated sites in PEGylated products could be elucidated with the tandem LC/MS methodology combining in-source fragmentation with CID-MS/MS. Both methodologies are applied to model PEGylated peptides to obtain the accurate masses and identify PEGylated sites.
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Affiliation(s)
- Lihua Huang
- Bioproduct Research & Development, Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Indianapolis, IN, USA.
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17
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Plesner B, Fee CJ, Westh P, Nielsen AD. Effects of PEG size on structure, function and stability of PEGylated BSA. Eur J Pharm Biopharm 2011; 79:399-405. [DOI: 10.1016/j.ejpb.2011.05.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 05/03/2011] [Accepted: 05/11/2011] [Indexed: 11/24/2022]
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18
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Li H, Rose MJ, Holder JR, Wright M, Miranda LP, James CA. Direct quantitative analysis of a 20 kDa PEGylated human calcitonin gene peptide antagonist in cynomolgus monkey serum using in-source CID and UPLC-MS/MS. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:1660-1667. [PMID: 21953269 DOI: 10.1007/s13361-011-0180-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 04/25/2011] [Accepted: 05/23/2011] [Indexed: 05/31/2023]
Abstract
PEGylation is a successful strategy to improve the pharmacokinetic and pharmaceutical properties of therapeutic peptides. However, quantitative analysis of PEGylated peptides in biomatrix by LC-MS/MS poses significant analytical challenge due to the polydispersity of the polyethylene glycol (PEG), and the multiple charge states observed for both the peptide and PEG moieties. In this report, a novel LC-MS/MS method for direct quantitative analysis of 20 kDa PEGylated CGRP[Cit, Cit] in cynomolgus monkey serum is presented. CGRP[Cit, Cit] is an investigational human calcitonin gene peptide receptor antagonist with amino acid sequence Ac -WVTH[Cit]LAGLLS[Cit]SGGVVRKNFVPT DVGPFAF-NH(2). In-source collision-induced dissociation (in-source CID) of 20 kDa PEGylated peptide was used to generate CGRP[Cit, Cit] fragment ions, among which the most abundant b(8)(+) ion was selected and measured as a surrogate for the 20 kDa PEGylated peptide. A solid phase extraction (SPE) method was used to extract the PEGylated peptides from the biomatrix prior to the UPLC-MS/MS analysis. This method achieved a lower limit of quantitation (LLOQ) of 5.00 ng/mL with a serum sample volume of 100 μL, and was linear over the calibration range of 5.00 to 500 ng/mL in cynomolgus monkey serum. Intraday and interday accuracy and precision from QC samples were within ±15%. This method was successfully applied to a pharmacokinetic study of the 20 kDa PEGylated CGRP[Cit, Cit] in cynomolgus monkeys.
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Affiliation(s)
- Hongyan Li
- Pharmacokinetics and Drug Metabolism, Amgen Inc., One Amgen Center Drive, Thousand Oaks, CA 91320, USA.
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19
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Bhatnagar BS, Martin SW, Hodge TS, Das TK, Joseph L, Teagarden DL, Shalaev EY, Suryanarayanan R. Investigation of PEG Crystallization in Frozen and Freeze‐Dried PEGylated Recombinant Human Growth Hormone–Sucrose Systems: Implications on Storage Stability. J Pharm Sci 2011; 100:3062-3075. [DOI: 10.1002/jps.22562] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 01/21/2011] [Accepted: 02/24/2011] [Indexed: 11/09/2022]
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20
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Top A, Roberts CJ, Kiick KL. Conformational and aggregation properties of a PEGylated alanine-rich polypeptide. Biomacromolecules 2011; 12:2184-92. [PMID: 21553871 DOI: 10.1021/bm200272w] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The conformational and aggregation behavior of PEG conjugates of an alanine-rich polypeptide (PEG-c17H6) were investigated and compared to that of the polypeptide equipped with a deca-histidine tag (17H6). These polypeptides serve as simple and stimuli-responsive models for the aggregation behavior of helix-rich proteins, as our previous studies have shown that the helical 17H6 self-associates at acidic pH and converts to β-sheet structures at elevated temperature under acidic conditions. In the work here, we show that PEG-c17H6 also adopts a helical structure at ambient/subambient temperatures, at both neutral and acidic pH. The thermal denaturation behavior of 17H6 and PEG-c17H6 is similar at neutral pH, where the alanine-rich domain has no self-association tendency. At acidic pH and elevated temperature, however, PEGylation slows β-sheet formation of c17H6, and reduces the apparent cooperativity of thermally induced unfolding. Transmission electron microscopy of PEG-c17H6 conjugates incubated at elevated temperatures showed fibrils with widths of ∼20-30 nm, wider than those observed for fibrils of 17H6. These results suggest that PEGylation reduces β-sheet aggregation in these polypeptides by interfering, only after unfolding of the native helical structure, with interprotein conformational changes needed to form β-sheet aggregates.
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Affiliation(s)
- Ayben Top
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA
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21
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Rodríguez-Martínez JA, Rivera-Rivera I, Griebenow K. Prevention of benzyl alcohol-induced aggregation of chymotrypsinogen by PEGylation. ACTA ACUST UNITED AC 2011; 63:800-5. [PMID: 21585378 DOI: 10.1111/j.2042-7158.2011.01288.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
OBJECTIVES Addition of the antimicrobial preservative benzyl alcohol to reconstitution buffer promotes the formation of undesirable aggregates in multidose protein formulations. Herein we investigated the efficiency of PEGylation (attachment of poly(ethylene glycol)) to prevent benzyl alcohol-induced aggregation of the model protein α-chymotrypsinogen A (aCTgn). METHODS Various PEG-aCTgn conjugates were prepared using PEG with a molecular weight of either 700 or 5000 Da by varying the PEG-to-protein ratio during synthesis and the formation of insoluble aggregates was studied. The effect of benzyl alcohol on the thermodynamic stability and tertiary structure of aCTgn was also examined. KEY FINDINGS When the model protein was reconstituted in buffer containing 0.9% benzyl alcohol, copious amounts of buffer-insoluble aggregates formed within 24 h (>10%). Benzyl alcohol-induced aggregation was completely prevented when two or five molecules of PEG with a molecular weight of 5000 Da were attached to the protein, whereas two or four molecules of bound 700 Da PEG were completely inefficient in preventing aggregation. Mechanistic investigations excluded prevention of structural perturbations or increased thermodynamic stability by PEGylation from being responsible for the prevention of aggregation. Simple addition of PEG to the buffer was also inefficient and PEG had to be covalently linked to the protein to be efficient. CONCLUSIONS The most likely explanation for the protective effect of the 5000 Da PEG is shielding of exposed hydrophobic protein surface area and prevention of protein-protein contacts (molecular spacer effect).
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22
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Sun J, Song X, Tian H, Jin Y, Gao X, Yao W. Synthesis of a novel histidine-targeting poly(ethylene glycol) and modification of lysozyme. J Appl Polym Sci 2011. [DOI: 10.1002/app.32908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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23
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Influence of PEGylation with linear and branched PEG chains on the adsorption of glucagon to hydrophobic surfaces. Eur J Pharm Biopharm 2011; 77:139-47. [DOI: 10.1016/j.ejpb.2010.11.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Revised: 10/30/2010] [Accepted: 11/03/2010] [Indexed: 11/21/2022]
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24
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25
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Peng HT, Huang Huang, Shek PN, Charbonneau S, Blostein MD. PEGylation of Melittin: Structural Characterization and Hemostatic Effects. J BIOACT COMPAT POL 2010. [DOI: 10.1177/0883911509354230] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To promote and understand the structure—property relationship for hemostasis, we modified melittin (MLT) using a four-arm poly(ethylene glycol) (PEG) with N-hydroxysuccinimide ester. The PEGylation was characterized by FTIR, MALDI-MS, NMR, a bicinchoninic acid assay, circular dichroism, hemolysis assay, and thromboelastography. Changes in the reaction conditions affected the extent of the modification, the numbers of MLT conjugated to PEG arms, and possible PEGylation sites. The reaction at pH 9.2 with a high MLT/PEG ratio, resulted in the highest modification. Reactions in dimethylsulfoxide (DMSO) resulted in more multi-arm coupled MLT, reaching a maximum of four MLT per PEG. The helicity of the modified peptide, relative to the native peptide, was essentially maintained in DMSO, but substantially lost at pH 9.2. PEGylation reduced the hemolytic effects of MLT and subsequently changed its coagulation profiles. The overall hemostatic effects of MLT modified in DMSO indicate that this may be a convenient approach to the PEGylation of biomolecules for biomedical applications.
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Affiliation(s)
- Henry T. Peng
- Defence Research and Development Canada - Toronto, 1133 Sheppard Avenue West, P.O. Box 2000, Toronto, Ontario, Canada,
| | - Huang Huang
- Defence Research and Development Canada - Toronto, 1133 Sheppard Avenue West, P.O. Box 2000, Toronto, Ontario, Canada
| | - Pang N. Shek
- Defence Research and Development Canada - Toronto, 1133 Sheppard Avenue West, P.O. Box 2000, Toronto, Ontario, Canada
| | - Sophie Charbonneau
- Lady Davis Institute of Medical Research, Jewish General Hospital McGill University, Montreal, Quebec, Canada
| | - Mark D. Blostein
- Lady Davis Institute of Medical Research, Jewish General Hospital McGill University, Montreal, Quebec, Canada
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26
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Wang X, Tian Y, Zhong G, Chen G. A Simple Method for Controlling the Degree of PEGylation of Dynorphin A (1-13). CHINESE J CHEM 2009. [DOI: 10.1002/cjoc.200990351] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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27
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Gunaseelan S, Pooyan S, Chen P, Samizadeh M, Palombo MS, Stein S, Zhang X, Sinko PJ. Multimeric peptide-based PEG nanocarriers with programmable elimination properties. Biomaterials 2009; 30:5649-59. [PMID: 19647312 DOI: 10.1016/j.biomaterials.2009.05.068] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Accepted: 05/21/2009] [Indexed: 11/16/2022]
Abstract
In the current study, the design, synthetic feasibility and biochemical characterization of biodegradable peptidic PEG-based nanocarriers are described. The components were selected to influence the body elimination pathway upon nanocarrier biodegradation. Two prototypical nanocarriers were prepared using non-PEGylated and PEGylated peptidic cores [CH(3)CO-(Lys-betaAla-betaAla)(X)-Cys-CONH(2) (X=2, 4)]. A homodimeric nanocarrier with 4 copies of fluorescein-PEG5kDa was synthesized by linking two PEGylated peptidic cores (X=2) using a disulfide bond. A dual labeled heterodimeric nanocarrier with 2 copies of fluorescein-PEG5kDa and 4 copies of Texas Red was also synthesized. Optimum conditions for linking imaging agents, PEG, or a peptidic core to a peptidic core were determined. Significantly higher yields (69% versus 30%) of the PEGylated peptidic core were obtained by using 2 copies of beta-alanine as a spacer along with increasing DMSO concentrations, which resulted in reduced steric hindrance. Stoichiometric addition of the components was also demonstrated and found to be important for reducing polydispersity. Nanocarrier biodegradation was evaluated in simulated intracellular and extracellular/blood environments using 3 mm and 10 microm glutathione in buffer, respectively. The nanocarrier was 9-fold more stable in the extracellular environment. The results suggest selective intracellular degradation of the nanocarrier into components with known body elimination pathways.
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Affiliation(s)
- Simi Gunaseelan
- Department of Pharmaceutics, Rutgers University, NJ 08854, USA
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28
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Yoo C, Suckau D, Sauerland V, Ronk M, Ma M. Toward top-down determination of PEGylation site using MALDI in-source decay MS analysis. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:326-333. [PMID: 19019698 DOI: 10.1016/j.jasms.2008.10.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 10/10/2008] [Accepted: 10/13/2008] [Indexed: 05/27/2023]
Abstract
A novel matrix assisted laser desorption/ionization (MALDI)-based mass spectrometric approach has been evaluated to rapidly analyze a custom designed PEGylated peptide that is 31 residues long and conjugated with 20 kDa linear polyethylene glycol (PEG) at the side chain of Lys. MALDI-TOF MS provided sufficiently high resolution to allow observation of each of the oligomers of the heterogeneous PEGylated peptide (m/Deltam of ca. 500), while a typical ESI-MS spectrum of this molecule was extremely complex and unresolved. Reflector in-source decay (reISD) analysis using MALDI-TOF MS was attempted to identify the PEGylation site at intact molecular level without any sample treatment. An reISD spectrum of the free peptide was observed with abundant c-, y-, and [z + 2]-fragment ion series, whereas, in the fragmented PEGylated peptide, the fragment ion series were truncated at the residue where PEG was attached. Therefore, a direct comparison of these top-down reISD spectra suggested the location of the PEGylation site. Results from this study demonstrate a clear analytical utility of the ISD technique to characterize structural aspects of heterogeneous biomolecules.
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Affiliation(s)
- Chul Yoo
- Analytical Research and Development, Amgen Inc., Thousand Oaks, California 91320, USA.
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Huang L, Gough PC, DeFelippis MR. Characterization of Poly(ethylene glycol) and PEGylated Products by LC/MS with Postcolumn Addition of Amines. Anal Chem 2008; 81:567-77. [DOI: 10.1021/ac801711u] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lihua Huang
- Bioproduct Research & Development, Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285
| | - P. Clayton Gough
- Bioproduct Research & Development, Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285
| | - Michael R. DeFelippis
- Bioproduct Research & Development, Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285
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Matilainen L, Maunu SL, Pajander J, Auriola S, Jääskeläinen I, Larsen KL, Järvinen T, Jarho P. The stability and dissolution properties of solid glucagon/gamma-cyclodextrin powder. Eur J Pharm Sci 2008; 36:412-20. [PMID: 19059479 DOI: 10.1016/j.ejps.2008.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 10/19/2008] [Accepted: 11/08/2008] [Indexed: 11/28/2022]
Abstract
In the present study, the solid-state stability and the dissolution of glucagon/gamma-cyclodextrin and glucagon/lactose powders were evaluated. Freeze-dried powders were stored at an increased temperature and/or humidity for up to 39 weeks. Pre-weighed samples were withdrawn at pre-determined intervals and analyzed with HPLC-UV (HPLC=high performance liquid chromatography, UV=ultraviolet), HPLC-ESI-MS (ESI-MS=electrospray ionization mass spectrometry), SEC (size-exclusion chromatography), turbidity measurements and solid-state FTIR (Fourier Transform Infrared Spectroscopy). Dissolution of glucagon was evaluated at pH 2.5, 5.0 and 7.0. In addition, before storage, proton rotating-frame relaxation experiments of solid glucagon/gamma-cyclodextrin powder were conducted with CPMAS ((13)C cross-polarization magic-angle spinning) NMR (nuclear magnetic resonance) spectroscopy. In the solid state, glucagon was degraded via oxidation and aggregation and in the presence of lactose via the Maillard reaction. The solid-state stability of glucagon/gamma-cyclodextrin powder was better than that of glucagon/lactose powder. In addition, gamma-cyclodextrin improved the dissolution of glucagon at pH 5.0 and 7.0 and delayed the aggregation of glucagon after its dissolution at pH 2.5, 5.0 and 7.0. There was no marked difference between the proton rotating-frame relaxation times of pure glucagon and gamma-cyclodextrin, and thus, the presence of inclusion complexes in the solid state could not be ascertained by CPMAS NMR. In conclusion, when compared to glucagon/lactose powder, glucagon/gamma-cyclodextrin powder exhibited better solid-state stability and more favorable dissolution properties.
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Affiliation(s)
- Laura Matilainen
- Department of Pharmaceutical Chemistry, University of Kuopio, P.O.Box 1627, FIN-70211 Kuopio, Finland
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31
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Svane ASP, Jahn K, Deva T, Malmendal A, Otzen DE, Dittmer J, Nielsen NC. Early stages of amyloid fibril formation studied by liquid-state NMR: the peptide hormone glucagon. Biophys J 2008; 95:366-77. [PMID: 18339765 PMCID: PMC2426625 DOI: 10.1529/biophysj.107.122895] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Accepted: 02/21/2008] [Indexed: 11/18/2022] Open
Abstract
The 29-residue peptide hormone glucagon forms amyloid fibrils within a few hours at low pH. In this study, we use glucagon as a model system to investigate fibril formation by liquid-state (1)H-NMR spectroscopy One-dimensional, correlation, and diffusion experiments monitoring the fibril formation process provide insight into the early stages of the pathway on which the molecules aggregate to fibrils. In conjunction with these techniques, exchange experiments give information about the end-state conformation. Within the limits of detection, there are no signs of larger oligomeric intermediates in the course of the fibril formation process. Kinetic information is extracted from the time course of the residual free glucagon signal decay. This suggests that glucagon amyloids form by a nucleated growth mechanism in which trimers (rather than monomers) of glucagon interact directly with the growing fibrils rather than with each other. The results of proton/deuterium exchange experiments on mature fibrils with subsequent dissolution show that the N-terminal of glucagon is the least amenable to exchange, which indicates that this part is strongly involved in the intermolecular bonds of the fibrils.
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Affiliation(s)
- Anna Sigrid Pii Svane
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, Denmark
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