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Jiráček J, Selicharová I, Žáková L. Mutations at hypothetical binding site 2 in insulin and insulin-like growth factors 1 and 2. VITAMINS AND HORMONES 2023; 123:187-230. [PMID: 37717985 DOI: 10.1016/bs.vh.2023.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Elucidating how insulin and the related insulin-like growth factors 1 and 2 (IGF-1 and IGF-2) bind to their cellular receptors (IR and IGF-1R) and how the receptors are activated has been the holy grail for generations of scientists. However, deciphering the 3D structure of tyrosine kinase receptors and their hormone-bound complexes has been complicated by the flexible and dimeric nature of the receptors and the dynamic nature of their interaction with hormones. Therefore, mutagenesis of hormones and kinetic studies first became an important tool for studying receptor interactions. It was suggested that hormones could bind to receptors through two binding sites on the hormone surface called site 1 and site 2. A breakthrough in knowledge came with the solution of cryoelectron microscopy (cryoEM) structures of hormone-receptor complexes. In this chapter, we document in detail the mutagenesis of insulin, IGF-1, and IGF-2 with emphasis on modifications of the hypothetical binding site 2 in the hormones, and we discuss the results of structure-activity studies in light of recent cryoEM structures of hormone complexes with IR and IGF-1R.
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Affiliation(s)
- Jiří Jiráček
- From Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic.
| | - Irena Selicharová
- From Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic
| | - Lenka Žáková
- From Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic
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2
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Engineering batch and pulse refolding with transition of aggregation kinetics: An investigation using green fluorescent protein (GFP). Chem Eng Sci 2015. [DOI: 10.1016/j.ces.2015.03.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Henderson ST, Brierley GV, Surinya KH, Priebe IK, Catcheside DEA, Wallace JC, Forbes BE, Cosgrove LJ. Delineation of the IGF-II C domain elements involved in binding and activation of the IR-A, IR-B and IGF-IR. Growth Horm IGF Res 2015; 25:20-27. [PMID: 25458127 DOI: 10.1016/j.ghir.2014.09.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 09/05/2014] [Accepted: 09/26/2014] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Human insulin-like growth factor-I and -II (IGF-I and -II) ligands share a high degree of sequence and structural homology. Despite their similarities, IGF-I and IGF-II exhibit differential receptor binding and activation characteristics. The C domains of IGF-I and IGF-II are the primary determinants of binding specificity to the insulin-like growth factor I receptor (IGF-IR), insulin receptor exon 11- (IR-A) and exon 11+ (IR-B) isoforms. DESIGN Three IGF-II analogues were generated in order to delineate the C domain residues that confer the differential receptor binding affinity and activation properties of the IGFs. Chimeric IGF-II analogues IGF-IICI(N) and IGF-IICI(C) contained partial IGF-I C domain substitutions (IGF-I residues underlined) GYGSSSRRSR and SRVSRRAPQT, respectively. RESULTS The IGF-IICI(N) analogue bound the IR-A and IGF-IR with high affinity but bound the IR-B with a relatively lower affinity than IGF-II, suggesting a negative interaction between the exon-11 encoded peptide in the IR-B and the C-domain. The ability of IGF-IICI(N) to activate receptors and elicit cell viability responses was generally proportional to its relative receptor binding affinity but appeared to act as a partial agonist equivalent to IGF-I when binding and activating the IGF-IR. In contrast, IGF-IICI(C) bound IGF-IR with high affinity but elicited lower receptor activation and cell viability responses. Analogue IGF-IICI(S) contained a truncated IGF-I C domain (GSSSRRAT) and generally displayed a relatively poor ability to bind, activate and elicit viability responses via each receptor. CONCLUSIONS Together, the IGF analogues demonstrate that both flanks of the IGF-II C domain play important roles in the greater ability of IGF-II to bind and activate IR receptors than IGF-I.
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Affiliation(s)
- S T Henderson
- Commonwealth Scientific Industrial Research Organisation, Preventative Health National Research Flagship, Adelaide, South Australia 5000, Australia; School of Biological Sciences, Flinders University, Adelaide, South Australia 5001, Australia
| | - G V Brierley
- Commonwealth Scientific Industrial Research Organisation, Preventative Health National Research Flagship, Adelaide, South Australia 5000, Australia
| | - K H Surinya
- Commonwealth Scientific Industrial Research Organisation, Preventative Health National Research Flagship, Adelaide, South Australia 5000, Australia
| | - I K Priebe
- Commonwealth Scientific Industrial Research Organisation, Preventative Health National Research Flagship, Adelaide, South Australia 5000, Australia
| | - D E A Catcheside
- School of Biological Sciences, Flinders University, Adelaide, South Australia 5001, Australia
| | - J C Wallace
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - B E Forbes
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - L J Cosgrove
- Commonwealth Scientific Industrial Research Organisation, Preventative Health National Research Flagship, Adelaide, South Australia 5000, Australia.
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Alvino CL, Ong SC, McNeil KA, Delaine C, Booker GW, Wallace JC, Forbes BE. Understanding the mechanism of insulin and insulin-like growth factor (IGF) receptor activation by IGF-II. PLoS One 2011; 6:e27488. [PMID: 22140443 PMCID: PMC3227035 DOI: 10.1371/journal.pone.0027488] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 10/18/2011] [Indexed: 12/29/2022] Open
Abstract
Background Insulin-like growth factor-II (IGF-II) promotes cell proliferation and survival and plays an important role in normal fetal development and placental function. IGF-II binds both the insulin-like growth factor receptor (IGF-1R) and insulin receptor isoform A (IR-A) with high affinity. Interestingly both IGF-II and the IR-A are often upregulated in cancer and IGF-II acts via both receptors to promote cancer proliferation. There is relatively little known about the mechanism of ligand induced activation of the insulin (IR) and IGF-1R. The recently solved IR structure reveals a folded over dimer with two potential ligand binding pockets arising from residues on each receptor half. Site-directed mutagenesis has mapped receptor residues important for ligand binding to two separate sites within the ligand binding pocket and we have recently shown that the IGFs have two separate binding surfaces which interact with the receptor sites 1 and 2. Methodology/Principal Findings In this study we describe a series of partial IGF-1R and IR agonists generated by mutating Glu12 of IGF-II. By comparing receptor binding affinities, abilities to induce negative cooperativity and potencies in receptor activation, we provide evidence that residue Glu12 bridges the two receptor halves leading to receptor activation. Conclusions/Significance This study provides novel insight into the mechanism of receptor binding and activation by IGF-II, which may be important for the future development of inhibitors of its action for the treatment of cancer.
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Affiliation(s)
- Clair L. Alvino
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, Australia
| | - Shee Chee Ong
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, Australia
| | - Kerrie A. McNeil
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, Australia
| | - Carlie Delaine
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, Australia
| | - Grant W. Booker
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, Australia
| | - John C. Wallace
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, Australia
| | - Briony E. Forbes
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, Australia
- * E-mail:
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Kashyap AS, Hollier BG, Manton KJ, Satyamoorthy K, Leavesley DI, Upton Z. Insulin-like growth factor-I:vitronectin complex-induced changes in gene expression effect breast cell survival and migration. Endocrinology 2011; 152:1388-401. [PMID: 21303956 DOI: 10.1210/en.2010-0897] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Recent studies have demonstrated that IGF-I associates with vitronectin (VN) through IGF-binding proteins (IGFBP), which in turn modulate IGF-stimulated biological functions such as cell proliferation, attachment, and migration. Because IGFs play important roles in transformation and progression of breast tumors, we aimed to describe the effects of IGF-I:IGFBP:VN complexes on breast cell function and to dissect mechanisms underlying these responses. In this study we demonstrate that substrate-bound IGF-I:IGFBP:VN complexes are potent stimulators of MCF-7 breast cell survival, which is mediated by a transient activation of ERK/MAPK and sustained activation of phosphoinositide 3-kinase/AKT pathways. Furthermore, use of pharmacological inhibitors of the MAPK and phosphoinositide 3-kinase pathways confirms that both pathways are involved in IGF-I:IGFBP:VN complex-mediated increased cell survival. Microarray analysis of cells stimulated to migrate in response to IGF-I:IGFBP:VN complexes identified differential expression of genes with previously reported roles in migration, invasion, and survival (Ephrin-B2, Sharp-2, Tissue-factor, Stratifin, PAI-1, IRS-1). These changes were not detected when the IGF-I analogue ([L(24)][A(31)]-IGF-I), which fails to bind to the IGF-I receptor, was substituted; confirming the IGF-I-dependent differential expression of genes associated with enhanced cell migration. Taken together, these studies have established that IGF-I:IGFBP:VN complexes enhance breast cell migration and survival, processes central to facilitating metastasis. This study highlights the interdependence of extracellular matrix and growth factor interactions in biological functions critical for metastasis and identifies potential novel therapeutic targets directed at preventing breast cancer progression.
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Affiliation(s)
- Abhishek S Kashyap
- Tissue Repair and Regeneration Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, 4059, Queensland, Australia.
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6
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Kolychev AP. Structural organization of binding determinants in the molecule of insulin-like growth factor-I (IGF-I). J EVOL BIOCHEM PHYS+ 2010. [DOI: 10.1134/s002209301001010x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Milner SJ, Thomas SM, Ballard FJ, Francis GL. Optimization of the hydroxylamine cleavage of an expressed fusion protein to produce recombinant human insulin-like growth factor (IGF)-I. Biotechnol Bioeng 2009; 50:265-72. [PMID: 18626954 DOI: 10.1002/(sici)1097-0290(19960505)50:3<265::aid-bit5>3.0.co;2-e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The application of gene fusion technology for the production of heterologous proteins in Escherichia coli has required the development of specific cleavage methods to separate the coexpressed fusion protein partner from the protein of interest. When hydroxylamine is used to cleave Asn-Gly fusion protein linkages, undesirable chemical modification of asparagine and glutamine amino acids can also occur. In this study, hydroxylamine cleavage conditions were modified to minimize unwanted chemical heterogeneity that occurred during the cleavage of the fusion protein [Met(1)]-pGH(1-11)-Val-Asn-IGF-I (Long-IGF-I). The cleavage reaction was shown to be dependent on the hydroxylamine concentration, temperature, and pH. Optimal cleavage conditions were identified that resulted in very low levels of chemical heterogeneity, but under these mild conditions that cleavage of the labile Asn-Gly bond was reduced. Therefore, the reaction was further modified to improve the yield of IGF-I while minimizing chemical heterogeneity. The yield of unmodified IGF-I was improved from less than 25% to greater than 70%. Analysis of the heterogeneity produced using the modified cleavage technique showed that Asn(26) was converted to a hydroxamate. This variant was characterized in refolding and biological assays where it was equivalent to IGF-I. To further assess the effectiveness of the modified cleavage technique and to evaluate the potential for process scale-up, a gram-scale cleavage reaction of Long-IGF-I was carried out. The process yielded IGF-I with a low level of chemical heterogeneity that was easily removed by ion-exchange chromatography. Moreover, this work shows that the production of unmodified IGFs using hydroxylamine cleavage of fusion proteins is facilitated using the mild cleavage reaction.
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Affiliation(s)
- S J Milner
- Cooperative Research Centre for Tissue Growth and Repair, P.O. Box 10065 Gouger Street, Adelaide, SA 5000, Australia
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8
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Hollier BG, Kricker JA, Van Lonkhuyzen DR, Leavesley DI, Upton Z. Substrate-bound insulin-like growth factor (IGF)-I-IGF binding protein-vitronectin-stimulated breast cell migration is enhanced by coactivation of the phosphatidylinositide 3-Kinase/AKT pathway by alphav-integrins and the IGF-I receptor. Endocrinology 2008; 149:1075-90. [PMID: 18079201 DOI: 10.1210/en.2007-0740] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
IGF-I can bind to the extracellular matrix protein vitronectin (VN) through the involvement of IGF-binding proteins-2, -3, -4, and -5. Because IGF-I and VN have established roles in tumor cell dissemination, we were keen to investigate the functional consequences of the interaction of IGF-I, IGF binding proteins (IGFBPs), and VN in tumor cell biology. Hence, functional responses of MCF-7 breast carcinoma cells and normal nontumorgenic MCF-10A mammary epithelial cells were investigated to allow side-by-side comparisons of these complexes in both cancerous and normal breast cells. We demonstrate that substrate-bound IGF-I-IGFBP-VN complexes stimulate synergistic increases in cellular migration in both cell types. Studies using IGF-I analogs determined this stimulation to be dependent on both heterotrimeric IGF-I-IGFBP-VN complex formation and the involvement of the IGF-I receptor (IGF-IR). Furthermore, the enhanced cellular migration was abolished on incubation of MCF-7 and MCF-10A cells with function blocking antibodies directed at VN-binding integrins and the IGF-IR. Analysis of the signal transduction pathways underlying the enhanced cell migration revealed that the complexes stimulate a transient activation of the ERK/MAPK signaling pathway while simultaneously producing a sustained activation of the phosphatidylinositide 3-kinase/AKT pathway. Experiments using pharmacological inhibitors of these pathways determined a requirement for phosphatidylinositide 3-kinase/AKT activation in the observed response. Overexpression of wild type and activated AKT further increases substrate-bound IGF-I-IGFBP-VN-stimulated migration. This study provides the first mechanistic insights into the action of IGF-I-IGFBP-VN complexes and adds further evidence to support the involvement of VN-binding integrins and their cooperativity with the IGF-IR in the promotion of tumor cell migration.
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Affiliation(s)
- Brett G Hollier
- Tissue Repair and Regeneration ProgramInstitute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Queensland 4059, Australia.
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Tokunou T, Miller R, Patwari P, Davis ME, Segers VFM, Grodzinsky AJ, Lee RT. Engineering insulin-like growth factor-1 for local delivery. FASEB J 2008; 22:1886-93. [PMID: 18285400 DOI: 10.1096/fj.07-100925] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Insulin-like growth factor-1 (IGF-1) is a small protein that promotes cell survival and growth, often acting over long distances. Although for decades IGF-1 has been considered to have therapeutic potential, systemic side effects of IGF-1 are significant, and local delivery of IGF-1 for tissue repair has been a long-standing challenge. In this study, we designed and purified a novel protein, heparin-binding IGF-1 (Xp-HB-IGF-1), which is a fusion protein of native IGF-1 with the heparin-binding domain of heparin-binding epidermal growth factor-like growth factor. Xp-HB-IGF-1 bound selectively to heparin as well as the cell surfaces of 3T3 fibroblasts, neonatal cardiac myocytes and differentiating ES cells. Xp-HB-IGF-1 activated the IGF-1 receptor and Akt with identical kinetics and dose response, indicating no compromise of biological activity due to the heparin-binding domain. Because cartilage is a proteoglycan-rich environment and IGF-1 is a known stimulus for chondrocyte biosynthesis, we then studied the effectiveness of Xp-HB-IGF-1 in cartilage. Xp-HB-IGF-1 was selectively retained by cartilage explants and led to sustained chondrocyte proteoglycan biosynthesis compared to IGF-1. These data show that the strategy of engineering a "long-distance" growth factor like IGF-1 for local delivery may be useful for tissue repair and minimizing systemic effects.
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Affiliation(s)
- Tomotake Tokunou
- Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Gauguin L, Klaproth B, Sajid W, Andersen AS, McNeil KA, Forbes BE, De Meyts P. Structural basis for the lower affinity of the insulin-like growth factors for the insulin receptor. J Biol Chem 2007; 283:2604-13. [PMID: 18048361 DOI: 10.1074/jbc.m709220200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin and the insulin-like growth factors (IGFs) bind with high affinity to their cognate receptor and with lower affinity to the noncognate receptor. The major structural difference between insulin and the IGFs is that the IGFs are single chain polypeptides containing A-, B-, C-, and D-domains, whereas the insulin molecule contains separate A- and B-chains. The C-domain of IGF-I is critical for high affinity binding to the insulin-like growth factor I receptor, and lack of a C-domain largely explains the low affinity of insulin for the insulin-like growth factor I receptor. It is less clear why the IGFs have lower affinity for the insulin receptor. In this study, 24 insulin analogues and four IGF analogues were expressed and analyzed to explore the role of amino acid differences in the A- and B-domains between insulin and the IGFs in binding affinity for the insulin receptor. Using the information obtained from single substituted analogues, four multiple substituted analogues were produced. A "quadruple insulin" analogue ([Phe(A8), Ser(A10), Thr(B5), Gln(B16)]Ins) showed affinity as IGF-I for the insulin receptor, and a "sextuple insulin" analogue ([Phe(A8), Ser(A10), Thr(A18), Thr(B5), Thr(B14), Gln(B16)]Ins) showed an affinity close to that of IGF-II for the insulin receptor, whereas a "quadruple IGF-I" analogue ([His(4), Tyr(15), Thr(49), Ile(51)]IGF-I) and a "sextuple IGF-II" analogue ([His(7), Ala(16), Tyr(18), Thr(48), Ile(50), Asn(58)]IGF-II) showed affinities similar to that of insulin for the insulin receptor. The mitogenic potency of these analogues correlated well with the binding properties. Thus, a small number of A- and B-domain substitutions that map to the IGF surface equivalent to the classical binding surface of insulin weaken two hotspots that bind to the insulin receptor site 1.
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Affiliation(s)
- Lisbeth Gauguin
- Receptor Systems Biology Laboratory, Hagedorn Research Institute, 2820 Gentofte, Denmark.
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11
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Insulin-like growth factor I releasing silk fibroin scaffolds induce chondrogenic differentiation of human mesenchymal stem cells. J Control Release 2007; 127:12-21. [PMID: 18280603 DOI: 10.1016/j.jconrel.2007.11.006] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 11/05/2007] [Accepted: 11/07/2007] [Indexed: 12/13/2022]
Abstract
Growth factor releasing scaffolds are an emerging alternative to autologous or allogenous implants, providing a biologically active template for tissue (re)-generation. The goal of this study is to evaluate the feasibility of controlled insulin-like growth factor I (IGF-I) releasing silk fibroin (SF) scaffolds in the context of cartilage repair. The impact of manufacturing parameters (pH, methanol treatment and drug load) was correlated with IGF-I release kinetics using ELISA and potency tests. Methanol treatment induced water insolubility of SF scaffolds, allowed the control of bioactive IGF-I delivery and did not affect IGF-I potency. The cumulative drug release correlated linearly with the IGF-I load. To evaluate the chondrogenic potential of the scaffolds, hMSC were seeded on unloaded and IGF-I loaded scaffolds in TGF-beta supplemented medium. Chondrogenic differentiation of hMSC was observed on IGF-I loaded scaffolds, starting after 2 weeks and more strongly after 3 weeks, whereas no chondrogenic responses were observed on unloaded control scaffolds. IGF-I loaded porous SF scaffolds have the potential to provide chondrogenic stimuli to hMSC. Evidence for in vivo cartilage (re)generation must be demonstrated by future, pre-clinical proof of concept studies.
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Delaine C, Alvino CL, McNeil KA, Mulhern TD, Gauguin L, De Meyts P, Jones EY, Brown J, Wallace JC, Forbes BE. A Novel Binding Site for the Human Insulin-like Growth Factor-II (IGF-II)/Mannose 6-Phosphate Receptor on IGF-II. J Biol Chem 2007; 282:18886-94. [PMID: 17475626 DOI: 10.1074/jbc.m700531200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mammalian insulin-like growth factor (IGF)-II/cation-independent mannose 6-phosphate receptor (IGF2R) binds IGF-II with high affinity. By targeting IGF-II to lysosomal degradation, it plays a role in the maintenance of correct IGF-II levels in the circulation and in target tissues. Loss of IGF2R function is associated with tumor progression; therefore, the IGF2R is often referred to as a tumor suppressor. The interaction between IGF2R and IGF-II involves domains 11 and 13 of the 15 extracellular domains of the receptor. Recently, a hydrophobic binding region was identified on domain 11 of the IGF2R. In contrast, relatively little is known about the residues of IGF-II that are involved in IGF2R binding and the determinants of IGF2R specificity for IGF-II over the structurally related IGF-I. Using a series of novel IGF-II analogues and surface plasmon resonance assays, this study revealed a novel binding surface on IGF-II critical for IGF2R binding. The hydrophobic residues Phe(19) and Leu(53) are critical for IGF2R binding, as are residues Thr(16) and Asp(52). Furthermore, Thr(16) was identified as playing a major role in determining why IGF-II, but not IGF-I, binds with high affinity to the IGF2R.
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Affiliation(s)
- Carlie Delaine
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia
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13
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Denley A, Wang CC, McNeil KA, Walenkamp MJE, van Duyvenvoorde H, Wit JM, Wallace JC, Norton RS, Karperien M, Forbes BE. Structural and functional characteristics of the Val44Met insulin-like growth factor I missense mutation: correlation with effects on growth and development. Mol Endocrinol 2004; 19:711-21. [PMID: 15576456 DOI: 10.1210/me.2004-0409] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We have previously described the phenotype resulting from a missense mutation in the IGF-I gene, which leads to expression of IGF-I with a methionine instead of a valine at position 44 (Val44Met IGF-I). This mutation caused severe growth and mental retardation as well as deafness evident at birth and growth retardation in childhood, but is relatively well tolerated in adulthood. We have conducted a biochemical and structural analysis of Val44Met IGF-I to provide a molecular basis for the phenotype observed. Val44Met IGF-I exhibits a 90-fold decrease in type 1 IGF receptor (IGF-1R) binding compared with wild-type human IGF-I and only poorly stimulates autophosphorylation of the IGF-1R. The ability of Val44Met IGF-I to signal via the extracellular signal-regulated kinase 1/2 and Akt/protein kinase B pathways and to stimulate DNA synthesis is correspondingly poorer. Binding or activation of both insulin receptor isoforms is not detectable even at micromolar concentrations. However, Val44Met IGF-I binds IGF-binding protein-2 (IGFBP-2), IGFBP-3, and IGFBP-6 with equal affinity to IGF-I, suggesting the maintenance of overall structure, particularly in the IGFBP binding domain. Structural analysis by nuclear magnetic resonance confirms retention of near-native structure with only local side-chain disruptions despite the significant loss of function. To our knowledge, our results provide the first structural study of a naturally occurring mutant human IGF-I associated with growth and developmental abnormalities and identifies Val44 as an essential residue involved in the IGF-IGF-1R interaction.
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Affiliation(s)
- Adam Denley
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, 5005 South Australia
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Denley A, Bonython ER, Booker GW, Cosgrove LJ, Forbes BE, Ward CW, Wallace JC. Structural determinants for high-affinity binding of insulin-like growth factor II to insulin receptor (IR)-A, the exon 11 minus isoform of the IR. Mol Endocrinol 2004; 18:2502-12. [PMID: 15205474 DOI: 10.1210/me.2004-0183] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The insulin receptor (IR) lacking the alternatively spliced exon 11 (IR-A) is preferentially expressed in fetal and cancer cells. The IR-A has been identified as a high-affinity receptor for insulin and IGF-II but not IGF-I, which it binds with substantially lower affinity. Several cancer cell types that express the IR-A also overexpress IGF-II, suggesting a possible autocrine proliferative loop. To determine the regions of IGF-I and IGF-II responsible for this differential affinity, chimeras were made where the C and D domains were exchanged between IGF-I and IGF-II either singly or together. The abilities of these chimeras to bind to, and activate, the IR-A were investigated. We also investigated the ability of these chimeras to bind and activate the IR exon 11+ isoform (IR-B) and as a positive control, the IGF-I receptor (IGF-1R). We show that the C domain and, to a lesser extent, the D domains represent the principal determinants of the binding differences between IGF-I and IGF-II to IR-A. The C and D domains of IGF-II promote higher affinity binding to the IR-A than the equivalent domains of IGF-I, resulting in an affinity close to that of insulin for the IR-A. The C and D domains also regulate the IR-B binding specificity of the IGFs in a similar manner, although the level of binding for all IGF ligands to IR-B is lower than to IR-A. In contrast, the C and D domains of IGF-I allow higher affinity binding to the IGF-1R than the analogous domains of IGF-II. Activation of IGF-1R by the chimeras reflected their binding affinities whereas the phosphorylation of the two IR isoforms was more complex.
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Affiliation(s)
- Adam Denley
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide 5005, Australia
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Buswell AM, Middelberg APJ. A new kinetic scheme for lysozyme refolding and aggregation. Biotechnol Bioeng 2003; 83:567-77. [PMID: 12827698 DOI: 10.1002/bit.10705] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The competing first- and third-order reaction scheme for lysozyme is shown to not predict fed-batch lysozyme refolding when the model is parameterized using independent batch experiments, even when variations in chemical composition during the fed-batch experiment are accounted for. A new kinetic scheme is proposed that involves rapid partitioning between the alternative fates of refolding and aggregation, and which allows for aggregation via a sequential mechanism. The model assumes that monomeric lysozyme in different states, including native, is able to aggregate with intermediates, accounting for recent experimental evidence that native protein can be incorporated into aggregates and explaining why native protein in the refolding buffer reduces yield. Stopped-flow light-scattering measurements were used to measure the association rate for the sequential aggregation mechanism, and refolding rate constants were determined in a series of batch experiments designed to be "snapshots" of the composition during a fed-batch experiment. The new kinetic scheme gave a good a priori prediction of fed-batch refolding performance.
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Affiliation(s)
- A Mark Buswell
- Department of Chemical Engineering, University of Cambridge, Pembroke Street, Cambridge CB2 3RA United Kingdom.
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Patel VA, Zhang QJ, Siddle K, Soos MA, Goddard M, Weissberg PL, Bennett MR. Defect in insulin-like growth factor-1 survival mechanism in atherosclerotic plaque-derived vascular smooth muscle cells is mediated by reduced surface binding and signaling. Circ Res 2001; 88:895-902. [PMID: 11348998 DOI: 10.1161/hh0901.090305] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Apoptosis of vascular smooth muscle cells (VSMCs) is increased in atherosclerosis compared with normal vessels, where it may contribute to plaque rupture. We have previously found that human plaque-derived VSMCs (pVSMCs) are intrinsically sensitive to apoptosis and not responsive to the protective effects of insulin-like growth factor-1 (IGF-1). We therefore examined the mechanism underlying this defect. Human pVSMCs showed <25% (125)I-IGF-1 surface binding, <20% IGF-1 receptor (IGF-1R) expression than that of normal medial VSMCs, and <40% Akt kinase activity in response to IGF-1. pVSMCs expressed and secreted high levels of IGF-1 binding proteins (IGFBPs), and the IGF-1 analogues, long R3 and Des 1,3 IGF-1, which do not bind to IGFBPs, were able to increase pVSMC survival to normal medial VSMC levels. The long R3 survival effect was phosphatidylinositol 3-kinase-mediated, but it was not dependent on Akt activity alone. Intimal pVSMCs in vivo showed reduced IGF-1R expression compared with medial VSMCs, in particular at the shoulder regions of plaques. We conclude that human pVSMCs show an intrinsic sensitivity to apoptosis caused in part by defective expression of IGF-1R, impaired IGF-1-mediated survival signaling and increased IGFBP secretion. This impaired IGF-1 protection against apoptosis may promote VSMC loss and plaque instability in atherosclerosis.
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MESH Headings
- Androstadienes/pharmacology
- Apoptosis/drug effects
- Arteriosclerosis/metabolism
- Arteriosclerosis/pathology
- Arteriosclerosis/prevention & control
- Cell Survival/drug effects
- Cells, Cultured
- Dose-Response Relationship, Drug
- Humans
- Immunohistochemistry
- Insulin-Like Growth Factor Binding Proteins/metabolism
- Insulin-Like Growth Factor I/metabolism
- Insulin-Like Growth Factor I/pharmacology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Protein Binding
- Protein Serine-Threonine Kinases
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-akt
- Radioligand Assay
- Receptor, IGF Type 1/metabolism
- Receptor, IGF Type 2/metabolism
- Signal Transduction/drug effects
- Time Factors
- Wortmannin
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Affiliation(s)
- V A Patel
- Departments of Medicine, Addenbrooke's Hospital, Cambridge, UK
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17
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Elminger MW, Bell M, Schüett BS, Langkamp M, Kutoh E, Ranke MB. Transactivation of the IGFBP-2 promoter in human tumor cell lines. Mol Cell Endocrinol 2001; 175:211-8. [PMID: 11325531 DOI: 10.1016/s0303-7207(00)00454-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Many cancers produce high amounts of the insulin-like growth factor binding protein (IGFBP)-2, which can influence the tumorigenicity and growth of tumor cells. In order to study the possible cause of elevated expression of IGFBP-2 in tumors, we investigated the transcriptional regulation by IGF of a 633-bp fragment of the human IGFBP-2 promoter in a transiently transfected choriocarcinoma (JAR) and a leukemic T-cell line (Molt-4) that express IGFBP-2 highly, and in a leukemic B-cell line (Raji) that expresses little IGFBP-2. Strong basal promoter activity, i.e. luciferase activity was measurable in all of the tumor cell lines. The introduction of equal amounts of normal IGF-I and IGF-II stimulated the transcription of IGFBP-2 only slightly. Synthetic IGF analogues with increased biological activity, however, caused a specific 2.0-3.3-fo1d transactivation of the promoter, as well as a 25% increase in IGFBP-2 mRNA. Synchronously, IGF analogues caused a decrease in the level of IGFBP-3 mRNA of about 45%, while the production of IGFBP-2 as measured by RIA increased in relation to IGFBP-3 by up to 15 times. Blocking with the IGF antagonist JB1 revealed partial involvement of the IGF-I receptor in the regulation of IGFBP-2 expression by locally produced IGF. We conclude, that the reduced ability of IGF analogues to form complexes with locally produced IGFBP may account for their increased biological activity in the stimulation of expression of IGFBP-2 and of cell growth. Since increased biological activity had also been demonstrated for natural pro-IGF forms often produced by tumors, pro-IGFs may be involved in the mechanism leading to elevated IGFBP-2 expression of tumors in vivo.
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Affiliation(s)
- M W Elminger
- Pediatric Endocrinology Section, University Children's Hospital, Hoppe-Seyler-Strasse, 72076, Tuebingen, Germany.
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18
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Qiao ZS, Guo ZY, Feng YM. Putative disulfide-forming pathway of porcine insulin precursor during its refolding in vitro. Biochemistry 2001; 40:2662-8. [PMID: 11258877 DOI: 10.1021/bi001613r] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although the structure of insulin has been well studied, the formation pathway of the three disulfide bridges during the refolding of insulin precursor is ambiguous. Here, we reported the in vitro disulfide-forming pathway of a recombinant porcine insulin precursor (PIP). In redox buffer containing L-arginine, the yield of native PIP from fully reduced/denatured PIP can reach 85%. The refolding process was quenched at different time points, and three distinct intermediates, including one with one disulfide linkage and two with two disulfide bridges, have been captured and characterized. An intra-A disulfide bridge was found in the former but not in the latter. The two intermediates with two disulfide bridges contain the common A20-B19 disulfide linkage and another inter-AB one. Based on the time-dependent formation and distribution of disulfide pairs in the trapped intermediates, two different forming pathways of disulfide bonds in the refolding process of PIP in vitro have been proposed. The first one involves the rapid formation of the intra-A disulfide bond, followed by the slower formation of one of the inter-AB disulfide bonds and then the pairing of the remaining cysteines to complete the refolding of PIP. The second pathway begins first with the formation of the A20-B19 disulfide bridge, followed immediately by another inter-AB one, possibly nonnative. The nonnative two-disulfide intermediates may then slowly rearrange between CysA6, CysA7, CysA11, and CysB7, until the native disulfide bond A6-A11 or A7-B7 is formed to complete the refolding of PIP. The proposed refolding behavior of PIP is compared with that of IGF-I and discussed.
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Affiliation(s)
- Z S Qiao
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, People's Republic of China
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19
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Lien S, Milner SJ, Graham LD, Wallace JC, Francis GL. Linkers for improved cleavage of fusion proteins with an engineered ?-lytic protease. Biotechnol Bioeng 2001. [DOI: 10.1002/bit.1124] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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Laajoki LG, Francis GL, Wallace JC, Carver JA, Keniry MA. Solution structure and backbone dynamics of long-[Arg(3)]insulin-like growth factor-I. J Biol Chem 2000; 275:10009-15. [PMID: 10744677 DOI: 10.1074/jbc.275.14.10009] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Long-[Arg(3)]insulin-like growth factor-I (IGF-I) is a potent analog of insulin-like growth factor-I that has been modified by a Glu(3) --> Arg mutation and a 13-amino acid extension appended to the N terminus. We have determined the solution structure of (15)N-labeled Long-[Arg(3)]-IGF-I using high resolution NMR and restrained molecular dynamics techniques to a precision of 0.82 +/- 0.28 A root mean square deviation for the backbone heavy atoms in the three alpha-helices and 3.5 +/- 0.9 A root mean square deviation for all backbone heavy atoms excluding the 8 N-terminal residues and the 8 C-terminal eight residues. Overall, the structure of the IGF-I domain is consistent with earlier studies of IGF-I with some minor changes remote from the N terminus. The major variations in the structure, compared with IGF-I, occur at the N terminus with a substantial reorientation of the N-terminal three residues of the IGF-I domain. These results are interpreted in terms of the lower binding affinity for insulin-like growth factor-binding proteins. The backbone dynamics of Long-[Arg(3)]IGF-I were investigated using (15)N nuclear spin relaxation and the heteronuclear nuclear Overhauser enhancement (NOE). There is a considerable degree of flexibility in Long-[Arg(3)]IGF-I, even in the alpha-helices, as indicated by an average ((1)H)(15)N NOE of 0.55 for the regions. The largest heteronuclear NOEs are observed in the helical regions, lower heteronuclear NOEs are observed in the C-domain loop separating helix 1 from helix 2, and negative heteronuclear NOEs are observed in the N-terminal extension and at the C terminus. Despite these data indicating conformational flexibility for the N-terminal extension, slow amide proton exchange was observed for some residues in this region, suggesting some transitory structure does exist, possibly a molten helix. A certain degree of flexibility may be necessary in all insulin-like growth factors to enable association with various receptors and binding proteins.
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Affiliation(s)
- L G Laajoki
- Research School of Chemistry, The Australian National University, Canberra, Australian Capital Territory 2601, South Australia 5000
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21
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Yang Y, Wu J, Watson JT. Probing the folding pathways of long R(3) insulin-like growth factor-I (LR(3)IGF-I) and IGF-I via capture and identification of disulfide intermediates by cyanylation methodology and mass spectrometry. J Biol Chem 1999; 274:37598-604. [PMID: 10608814 DOI: 10.1074/jbc.274.53.37598] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This report describes an integrated investigation of the refolding and reductive unfolding of insulin-like growth factor (IGF-I) and its variant, long R(3) IGF-I (LR(3)IGF-I), which has a Glu(3) to Arg(3) substitution and a hydrophobic 13-amino acid N-terminal extension. The refolding performed in glutathione redox buffer was quenched at different time points by adjusting the pH to 2.0-3.0 with a 1 N HCl solution of 1-cyano-4-dimethylaminopyridinium tetrafluoroborate, which trapped intermediates via cyanylation of free sulfhydryl groups. The disulfide structure of the intermediates was determined by chemical cleavage followed by mass mapping with mass spectrometry. Six refolding intermediates of IGF-I and three refolding intermediates of LR(3)IGF-I were isolated and characterized. Folding pathways of IGF-I and LR(3)IGF-I are proposed based on the time-dependent distribution and disulfide structure of the corresponding trapped intermediates. Similarities and differences in the refolding behavior of IGF-I and LR(3)IGF-I are discussed.
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Affiliation(s)
- Y Yang
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
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22
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Magee BA, Shooter GK, Wallace JC, Francis GL. Insulin-like growth factor I and its binding proteins: a study of the binding interface using B-domain analogues. Biochemistry 1999; 38:15863-70. [PMID: 10625451 DOI: 10.1021/bi9910070] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biological activity of the insulin-like growth factors (IGF-I and IGF-II) is regulated by six IGF binding proteins (IGFBPs 1-6). To examine the surface of IGF-I that associates with the IGFBPs, we created a series of six IGF-I analogues, [His(4)]-, [Gln(9)]-, [Lys(9)]-, [Ser(16)]-, [Gln(9),Ser(16)]-, and [Lys(9),Ser(16)]IGF-I, that contained substitutions for residues Thr(4), Glu(9), or Phe(16). Substitution of Ser for Phe(16) did not affect secondary structure but significantly decreased the affinity for all IGFBPs by between 14-fold and >330-fold, indicating that Phe(16) is functionally important for IGFBP association. While His(4) or Gln(9) substitutions had little effect on IGFBP affinity, changing the negative charge of Glu(9) to a positive Lys(9) selectively decreased the affinities of IGFBP-2 and -6 by 140- and 30-fold, respectively. Furthermore, the effects of mutations to both residues 9 and 16 appear to be additive. The analogues are biologically active in rat L6 myoblasts and they retain native structure as assessed by their far-UV circular dichroism (CD) profiles. We propose that Phe(16) and adjacent hydrophobic residues (Leu(5) and Leu(54)) form a functional binding pocket for IGFBP association.
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Affiliation(s)
- B A Magee
- Cooperative Research Center for Tissue Growth and Repair, Department of Biochemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
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23
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24
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Yang Y, Wu J, Watson JT. Disulfide Mass Mapping in Proteins Containing Adjacent Cysteines Is Possible with Cyanylation/Cleavage Methodology. J Am Chem Soc 1998. [DOI: 10.1021/ja9736018] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ying Yang
- Departments of Chemistry and Biochemistry Michigan State University East Lansing, Michigan 48824-1319
| | - Jiang Wu
- Departments of Chemistry and Biochemistry Michigan State University East Lansing, Michigan 48824-1319
| | - J. Throck Watson
- Departments of Chemistry and Biochemistry Michigan State University East Lansing, Michigan 48824-1319
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25
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Antorini M, Breme U, Caccia P, Grassi C, Lebrun S, Orsini G, Taylor G, Valsasina B, Marengo E, Todeschini R, Andersson C, Gellerfors P, Gustafsson JG. Hydroxylamine-induced cleavage of the asparaginyl-glycine motif in the production of recombinant proteins: the case of insulin-like growth factor I. Protein Expr Purif 1997; 11:135-47. [PMID: 9325149 DOI: 10.1006/prep.1997.0771] [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: 02/05/2023]
Abstract
Hydroxylamine-induced cleavage at the asparaginyl-glycine dipeptide site inserted between the two moieties of recombinant fusion proteins has been used at both the analytical and the preparative scale to obtain the mature protein. In this study a model protein containing a fusion precursor of insulin-like growth factor I was used to investigate the influence of the operating conditions on the cleavage reaction and the formation of undesired side products such as hydroxamate and deamidated analogs. Moreover, the stability of the cleavage site toward deamidation was examined and a chemometric study performed to define the effect of the reaction conditions on the cleavage yield and on the formation of side products.
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