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Volumn 29, Issue 1, 2012, Pages 209-224

Elucidation of degradants in acidic peak of cation exchange chromatography in an IgG1 monoclonal antibody formed on long-term storage in a liquid formulation

Author keywords

Acidic peak; Cation exchange chromatography; Deamidation; IgGImonoclonal antibody; Protein formulation

Indexed keywords

FC RECEPTOR; GLUTAMINE; IMMUNOGLOBULIN G1 ANTIBODY; MONOCLONAL ANTIBODY; SIALIC ACID; TRYPSIN; ASPARAGINE; ASPARTIC ACID; FC RECEPTOR, NEONATAL; HLA ANTIGEN CLASS 1; IMMUNOGLOBULIN G;

EID: 84860557842     PISSN: 07248741     EISSN: 1573904X     Source Type: Journal    
DOI: 10.1007/s11095-011-0536-0     Document Type: Article
Times cited : (54)

References (50)
  • 2
    • 0032782071 scopus 로고    scopus 로고
    • Instability, stabilization, and formulation of liquid protein pharmaceuticals
    • DOI 10.1016/S0378-5173(99)00152-0, PII S0378517399001520
    • Wang W. Instability, stabilization, and formulation of liquid protein pharmaceuticals. Int J Pharm. 1999;185:129-88. (Pubitemid 29392904)
    • (1999) International Journal of Pharmaceutics , vol.185 , Issue.2 , pp. 129-188
    • Wang, W.1
  • 4
    • 0026713528 scopus 로고
    • Deamidation: A source of microheterogeneity in pharmaceutical proteins
    • Liu D. Deamidation: a source of microheterogeneity in pharmaceutical proteins. Trends Biotechnol. 1992;10:364-9.
    • (1992) Trends Biotechnol , vol.10 , pp. 364-369
    • Liu, D.1
  • 5
    • 0033988464 scopus 로고    scopus 로고
    • Isoaspartate in peptides and proteins: Formation, significance, and analysis
    • DOI 10.1016/S0731-7085(99)00230-7, PII S0731708599002307
    • Aswad D, Paranandi M, Schuter B. Isoaspartate in peptides and proteins: formation, significance, and analysis. J Pharm Biomed Anal. 2000;21:1129-36. (Pubitemid 30001541)
    • (2000) Journal of Pharmaceutical and Biomedical Analysis , vol.21 , Issue.6 , pp. 1129-1136
    • Aswad, D.W.1    Paranandi, M.V.2    Schurter, B.T.3
  • 6
    • 33845450543 scopus 로고    scopus 로고
    • Cation exchange-HPLC and mass spectrometry reveal C-terminal amidation of an IgG1 heavy chain
    • DOI 10.1016/j.ab.2006.10.012, PII S0003269706007317
    • Johnson K, Paisley-Flango K, Tangarone B, Porter T, Rouse J. Cation exchange-HPLC and mass spectrometry reveal C-terminal amidation of an IgG1 heavy chain. Anal Biochem. 2006;360:75-83. (Pubitemid 44894347)
    • (2007) Analytical Biochemistry , vol.360 , Issue.1 , pp. 75-83
    • Johnson, K.A.1    Paisley-Flango, K.2    Tangarone, B.S.3    Porter, T.J.4    Rouse, J.C.5
  • 7
    • 0033755938 scopus 로고    scopus 로고
    • Determination of the origin of charge heterogeneity in a murine monoclonal antibody
    • Perkins M, Theiler R, Lunte S, Jeschke M. Determination of the origin of charge heterogeneity in a murine monoclonal antibody. Pharm Res. 2000;17:1110-7.
    • (2000) Pharm Res , vol.17 , pp. 1110-1117
    • Perkins, M.1    Theiler, R.2    Lunte, S.3    Jeschke, M.4
  • 8
    • 0035258289 scopus 로고    scopus 로고
    • Protein variant separations using cation exchange chromatography on grafted, polymeric stationary phases
    • Weitzhandler M, Farnan D, Rohrer J, Avdalovic N. Protein variant separations using cation exchange chromatography on grafted, polymeric stationary phases. Proteomics. 2001;1:179-85. (Pubitemid 33586713)
    • (2001) Proteomics , vol.1 , Issue.2 , pp. 179-185
    • Weitzhandler, M.1    Farnan, D.2    Rohrer, J.S.3    Avdalovic, N.4
  • 9
    • 0032545518 scopus 로고    scopus 로고
    • Protein variant separations by cation-exchange chromatography on tentacle-type polymeric stationary phases
    • DOI 10.1016/S0021-9673(98)00521-4, PII S0021967398005214
    • Weitzhandler M, Farnan D, Horwath J, Rohrer J, Slingsby R, Avdalovic N, et al. Protein variant separations by cation-exchange chromatography on tentacle-type polymeric stationary phases. J Chromatogr A. 1998;828:365-72. (Pubitemid 29046436)
    • (1998) Journal of Chromatography A , vol.828 , Issue.1-2 , pp. 365-372
    • Weitzhandler, M.1    Farnan, D.2    Horvath, J.3    Rohrer, J.S.4    Slingsby, R.W.5    Avdalovic, N.6    Pohl, C.7
  • 11
    • 60849102492 scopus 로고    scopus 로고
    • Heterogeneity of monoclonal antibodies revealed by charge-sensitive methods
    • Vlasak J, Ionescu R. Heterogeneity of monoclonal antibodies revealed by charge-sensitive methods. Curr Pharm Biotechnol. 2008;9:468-81.
    • (2008) Curr Pharm Biotechnol , vol.9 , pp. 468-481
    • Vlasak, J.1    Ionescu, R.2
  • 12
    • 33750955290 scopus 로고    scopus 로고
    • Formulation considerations for proteins susceptible to asparagine deamidation and aspartate isomerization
    • DOI 10.1002/jps.20740
    • Wakankar A, Borchardt R. Formulation considerations for proteins susceptible to asparagine deamidation and aspartate isomerization. J Pharm Sci. 2006;95:2321-36. (Pubitemid 44732136)
    • (2006) Journal of Pharmaceutical Sciences , vol.95 , Issue.11 , pp. 2321-2336
    • Wakankar, A.A.1    Borchardt, R.T.2
  • 13
    • 37049078890 scopus 로고
    • Kinetics and mechanism of succinimide ring formation in the deamidation process of asparagine residues
    • Capasso S, Mazzarella L, Sica F, Zagari A, Salvadori S. Kinetics and mechanism of succinimide ring formation in the deamidation process of asparagine residues. J Chem Soc, Perkin Trans. 1993;2:679-82.
    • (1993) J Chem Soc, Perkin Trans , vol.2 , pp. 679-682
    • Capasso, S.1    Mazzarella, L.2    Sica, F.3    Zagari, A.4    Salvadori, S.5
  • 14
    • 0025114552 scopus 로고
    • Chemical pathways of peptide degradation. III. effect of primary sequence on the pathways of deamidation of asparaginyl residues in hexapeptides
    • Patel K, Borchardt R. Chemical pathways of peptide degradation. III. Effect of primary sequence on the pathways of deamidation of asparaginyl residues in hexapeptides. Pharm Res. 1990;7:787-93. (Pubitemid 20332529)
    • (1990) Pharmaceutical Research , vol.7 , Issue.8 , pp. 787-793
    • Patel, K.1    Borchardt, R.T.2
  • 15
    • 0027463564 scopus 로고
    • Chemical pathways of peptide degradation. IV. Pathways, kinetics, and mechanism of degradation of an aspartyl residue in a model hexapeptide
    • DOI 10.1023/A:1018981231468
    • Oliyai C, Borchardt R. Chemical pathways of peptide degradation. IV. Pathways, kinetics, and mechanism of degradation of an aspartyl residue in a model hexapeptide. Pharm Res. 1993;10:95-102. (Pubitemid 23020844)
    • (1993) Pharmaceutical Research , vol.10 , Issue.1 , pp. 95-102
    • Oliyai, C.1    Borchardt, R.T.2
  • 16
    • 0035137491 scopus 로고    scopus 로고
    • Effect of "pH" on the rate of asparagine deamidation in polymeric formulations: "pH"-rate profile
    • DOI 10.1002/1520-6017(200102)90:2<141::AID-JPS5>3.0.CO;2-Y
    • Song Y, Schowen R, Borchardt R, Topp E. Effect of 'pH' on the rate of asparagine deamidation in polymeric formulations: 'pH'-rate profile. J Pharm Sci. 2001;90:141-56. (Pubitemid 32158042)
    • (2001) Journal of Pharmaceutical Sciences , vol.90 , Issue.2 , pp. 141-156
    • Song, Y.1    Schowen, R.L.2    Borchardt, R.T.3    Topp, E.M.4
  • 17
    • 0023109951 scopus 로고
    • Deamidation, isomerization, and racemization at asparaginyl and aspartyl residues in peptides. Succinimide-linked reactions that contribute to protein degradation
    • Geiger T, Clarke S. Deamidation, isomerization, and racemization at asparaginyl and aspartyl residues in peptides. Succinimidelinked reactions that contribute to protein degradation. J Biol Chem. 1987;262:785-94. (Pubitemid 17005254)
    • (1987) Journal of Biological Chemistry , vol.262 , Issue.2 , pp. 785-794
    • Geiger, T.1    Clarke, S.2
  • 18
    • 0025024815 scopus 로고
    • Chemical pathways of peptide degradation. II. Kinetics of deamidation of an asparaginyl residue in a model hexapeptide
    • DOI 10.1023/A:1015807303766
    • Patel K, Borchardt RT. Chemical pathways of peptide degradation: II. Kinetics of deamidation of an asparaginyl residue in a model hexapeptide. Pharm Res. 1990;7:703-11. (Pubitemid 20278366)
    • (1990) Pharmaceutical Research , vol.7 , Issue.7 , pp. 703-711
    • Patel, K.1    Borchardt, R.T.2
  • 19
    • 0032743230 scopus 로고    scopus 로고
    • The effects of alpha-helix on the stability of Asn residues: Deamidation rates in peptides of varying helicity
    • Kosky AA, Razzaq UO, Treuheit MJ, Brems DN. The effects of α-helix on the stability of Asn residues: deamidation rates in peptides of varying helicity. Protein Sci. 1999;8:2519-23. (Pubitemid 29536421)
    • (1999) Protein Science , vol.8 , Issue.11 , pp. 2519-2523
    • Kosky, A.A.1    Razzaq, U.O.2    Treuheit, M.J.3    Brems, D.N.4
  • 21
    • 0034002560 scopus 로고    scopus 로고
    • Estimation of the deamidation rate of asparagine side chains
    • DOI 10.1034/j.1399-3011.2000.00172.x
    • Capasso S. Estimation of the deamidation rate of asparagine side chains. J Pept Res. 2000;55:224-9. (Pubitemid 30126656)
    • (2000) Journal of Peptide Research , vol.55 , Issue.3 , pp. 224-229
    • Capasso, S.1
  • 22
    • 0028260569 scopus 로고
    • Chemical pathways of peptide degradation. VI. Effect of the primary sequence on the pathways of degradation of aspartyl residues in model hexapeptides
    • DOI 10.1023/A:1018944800691
    • Oliyai C, Borchardt R. Chemical pathways of peptide degradation. VI. Effect of the primary sequence on the pathways of degradation of aspartyl residues in model hexapeptides. PharmRes. 1994;11:751-8. (Pubitemid 24171774)
    • (1994) Pharmaceutical Research , vol.11 , Issue.5 , pp. 751-758
    • Oliyai, C.1    Borchardt, R.T.2
  • 24
    • 70349229289 scopus 로고    scopus 로고
    • Succinimide formation at Asn 55 in the complementarity determining region of a recombinant monoclonal antibody IgG1 heavy chain
    • Yan B, Steen S, Hambly D, Valliere-Douglass J, Bos T, Smallwood S, et al. Succinimide formation at Asn 55 in the complementarity determining region of a recombinant monoclonal antibody IgG1 heavy chain. J Pharm Sci. 2009;98:3509-21.
    • (2009) J Pharm Sci , vol.98 , pp. 3509-3521
    • Yan, B.1    Steen, S.2    Hambly, D.3    Valliere-Douglass, J.4    Bos, T.5    Smallwood, S.6
  • 25
    • 51949099133 scopus 로고    scopus 로고
    • Hydrophobic interaction chromatography of soluble interleukin I receptor type II to reveal chemical degradations resulting in loss of potency
    • Zhang Y, Martinez T, Woodruff B, Goetze A, Bailey R, Pettit D, et al. Hydrophobic interaction chromatography of soluble interleukin I receptor type II to reveal chemical degradations resulting in loss of potency. Anal Chem. 2008;80:7022-8.
    • (2008) Anal Chem , vol.80 , pp. 7022-7028
    • Zhang, Y.1    Martinez, T.2    Woodruff, B.3    Goetze, A.4    Bailey, R.5    Pettit, D.6
  • 26
    • 0028140248 scopus 로고
    • Deamidation and isoaspartate formation during in vitro aging of recombinant tissue plasminogen activator
    • Paranandi M, Guzzetta A, Hancock W, Aswad D. Deamidation and isoaspartate formations during in vitro aging of recombinant tissue plasminogen activator. J Biol Chem. 1994;269:243-53. (Pubitemid 24026651)
    • (1994) Journal of Biological Chemistry , vol.269 , Issue.1 , pp. 243-253
    • Paranandi, M.V.1    Guzzetta, A.W.2    Hancock, W.S.3    Aswad, D.W.4
  • 27
    • 0027254040 scopus 로고
    • Comparison of separation and detection techniques for human growth hormone releasing factor (hGRF) and the products derived from deamidation
    • DOI 10.1016/0731-7085(93)80030-5
    • Stevenson C, Anderegg R, Borchardt R. Comparison of separation and detection techniques for human growth hormone releasing factor (hGRF) and the products from deamidation. J Pharm Biomed Anal. 1993;11:367-73. (Pubitemid 23201948)
    • (1993) Journal of Pharmaceutical and Biomedical Analysis , vol.11 , Issue.4-5 , pp. 367-373
    • Stevenson, C.L.1    Anderegg, R.J.2    Borchardt, R.T.3
  • 29
    • 24944512327 scopus 로고    scopus 로고
    • Identification and characterization of deamidation sites in the conserved regions of human immunoglobulin gamma antibodies
    • DOI 10.1021/ac050672d
    • Chelius D, Rehder D, Bondarenko P. Identification and characterization of deamidation sites in the conserved regions of human immunoglobulin gamma antibodies. Anal Chem. 2005;77:6004-11. (Pubitemid 41324303)
    • (2005) Analytical Chemistry , vol.77 , Issue.18 , pp. 6004-6011
    • Chelius, D.1    Render, D.S.2    Bondarenko, P.V.3
  • 30
    • 34447307909 scopus 로고    scopus 로고
    • 18O
    • DOI 10.1016/j.ab.2007.05.012, PII S0003269707003120
    • Terashima I, Koga A, Nagai H. Identification of deamidation and isomerization sites on pharmaceutical recombinant antibody using H218O. Anal Biochem. 2007;368:49-60. (Pubitemid 47058431)
    • (2007) Analytical Biochemistry , vol.368 , Issue.1 , pp. 49-60
    • Terashima, I.1    Koga, A.2    Nagai, H.3
  • 31
    • 67649311402 scopus 로고    scopus 로고
    • An improved trypsin digestion method minimizes digestioninduced modifications on proteins
    • Ren D, Pipes GD, Liu D, Shih L, Nichols AC, Treuheit MJ, et al. An improved trypsin digestion method minimizes digestioninduced modifications on proteins. Anal Biochem. 2009;393:12-21.
    • (2009) Anal Biochem , vol.393 , pp. 12-21
    • Ren, D.1    Pipes, G.D.2    Liu, D.3    Shih, L.4    Nichols, A.C.5    Treuheit, M.J.6
  • 32
    • 0028307232 scopus 로고
    • Infrared methods for study of hemoglobin reactions and structures
    • Dong A, Caughey WS. Infrared methods for study of hemoglobin reactions and structures. Meth Enzymol. 1994;232:139-75.
    • (1994) Meth Enzymol , vol.232 , pp. 139-175
    • Dong, A.1    Caughey, W.S.2
  • 33
    • 0030059491 scopus 로고    scopus 로고
    • Quantitation of the area of overlap between second-derivative amide I infrared spectra to determine the structural similarity of a protein in different states
    • DOI 10.1021/js950332f
    • Kendrick BS, Dong A, Allison SD, Manning MC, Carpenter JF. Quantitation of the area of overlap between second-derivative amide I infrared spectra to determine the structural similarity of a protein in different states. J Pharm Sci. 1996;85:155-8. (Pubitemid 26055795)
    • (1996) Journal of Pharmaceutical Sciences , vol.85 , Issue.2 , pp. 155-158
    • Kendrick, B.S.1    Dong, A.2    Allison, S.D.3    Manning, M.C.4    Carpenter, J.F.5
  • 34
    • 3242660851 scopus 로고    scopus 로고
    • Prediction of low-energy collision-induced dissociation spectra of peptides
    • DOI 10.1021/ac049951b
    • Zhang Z. Prediction of low-energy collision-induced dissociation spectra of peptides. Anal Chem. 2004;76:3908-22. (Pubitemid 38943659)
    • (2004) Analytical Chemistry , vol.76 , Issue.14 , pp. 3908-3922
    • Zhang, Z.1
  • 35
    • 7644230941 scopus 로고    scopus 로고
    • De novo peptide sequencing based on a divide-and-conquer algorithm and peptide tandem spectrum simulation
    • DOI 10.1021/ac0491206
    • Zhang Z. De novo peptide sequencing based on a divide-andconquer algorithm and peptide tandem spectrum simulation. Anal Chem. 2004;76:6374-83. (Pubitemid 39458471)
    • (2004) Analytical Chemistry , vol.76 , Issue.21 , pp. 6374-6383
    • Zhang, Z.1
  • 36
    • 70450078402 scopus 로고    scopus 로고
    • Large-scale identification and modification of covalent modifications on therapeutic proteins
    • Zhang Z. Large-scale identification and modification of covalent modifications on therapeutic proteins. Anal Chem. 2009;81:8354-64.
    • (2009) Anal Chem , vol.81 , pp. 8354-8364
    • Zhang, Z.1
  • 37
    • 0030683957 scopus 로고    scopus 로고
    • Capillary isoelectric focusing and high-performance cation-exchange chromatography compared for qualitative and quantitative analysis of hemoglobin variants
    • Mario N, Baudin B, Aussel C, Giboudeau J. Capillary isoelectric focusing and high-performance cation-exchange chromatography compared for qualitative and quantitative analysis of hemoglobin variants. Clin Chem. 1997;43:2137-42. (Pubitemid 27497813)
    • (1997) Clinical Chemistry , vol.43 , Issue.11 , pp. 2137-2142
    • Mario, N.1    Baudin, B.2    Aussel, C.3    Giboudeau, J.4
  • 39
    • 0033613146 scopus 로고    scopus 로고
    • Characterization of the 2:1 complex between the class I MHC-related Fc receptor and its Fc ligand in solution
    • Martin W, Bjorkman P. Characterization of the 2:1 complex between the class I MHC-related Fc receptor and its Fc ligand in solution. Biochemistry. 1999;38:12639-47.
    • (1999) Biochemistry , vol.38 , pp. 12639-12647
    • Martin, W.1    Bjorkman, P.2
  • 40
    • 69749112012 scopus 로고    scopus 로고
    • Detection and quantitation of IgG 1 hinge aspartate isomerization: The fastest degradation in stressed stability studies
    • Hambly DM, Banks DD, Scavezze JL, Siska CC, Gadgil HS. Detection and quantitation of IgG 1 hinge aspartate isomerization: the fastest degradation in stressed stability studies. Anal Chem. 2009;81:7454-9.
    • (2009) Anal Chem , vol.81 , pp. 7454-7459
    • Hambly, D.M.1    Banks, D.D.2    Scavezze, J.L.3    Siska, C.C.4    Gadgil, H.S.5
  • 41
    • 72149128484 scopus 로고    scopus 로고
    • Identification and measurement of isoaspartic acid formation in the complementarity determiningregion of a fully human monoclonal antibody
    • Dick Jr LW, Qiu D, Cheng K. Identification and measurement of isoaspartic acid formation in the complementarity determiningregion of a fully human monoclonal antibody. J Chromatogr B. 2009;877:3841-9.
    • (2009) J Chromatogr B , vol.877 , pp. 3841-3849
    • Dick Jr., L.W.1    Qiu, D.2    Cheng, K.3
  • 42
    • 77949487806 scopus 로고    scopus 로고
    • Investigation of degradation processes in IgG1 monoclonal antibodies by limited proteolysis coupled with weak cation exchange HPLC
    • Lau H, Pace D, Yan B, McGrath T, Smallwood S, Patel K, et al. Investigation of degradation processes in IgG1 monoclonal antibodies by limited proteolysis coupled with weak cation exchange HPLC. J Chromatogr B. 2010;878:868-76.
    • (2010) J Chromatogr B , vol.878 , pp. 868-876
    • Lau, H.1    Pace, D.2    Yan, B.3    McGrath, T.4    Smallwood, S.5    Patel, K.6
  • 43
    • 37749041309 scopus 로고    scopus 로고
    • A study in glycation of a therapeutic recombinant humanized monoclonal antibody: Where it is, how it got there, and how it affects charge-based behavior
    • Quan C, Alcala E, Petkovska I, Matthews D, Canova-Davis E, Taticek R, et al. A study in glycation of a therapeutic recombinant humanized monoclonal antibody: where it is, how it got there, and how it affects charge-based behavior. Anal Biochem. 2008;373:179-91.
    • (2008) Anal Biochem , vol.373 , pp. 179-191
    • Quan, C.1    Alcala, E.2    Petkovska, I.3    Matthews, D.4    Canova-Davis, E.5    Taticek, R.6
  • 45
    • 0041367295 scopus 로고    scopus 로고
    • Deamidation and isoaspartate formation in proteins: Unwanted alterations or surreptitious signals?
    • DOI 10.1007/s00018-003-2287-5
    • Reissner KJ, Aswad DW. Deamidation and isoaspartate formation in proteins: unwanted alterations or surreptitious signals? Cell Mol Life Sci. 2003;60:1281-95. (Pubitemid 36900513)
    • (2003) Cellular and Molecular Life Sciences , vol.60 , Issue.7 , pp. 1281-1295
    • Reissner, K.J.1    Aswad, D.W.2
  • 46
    • 1842525890 scopus 로고    scopus 로고
    • Asparagine deamidation: A regulatory hourglass
    • DOI 10.1016/j.mad.2004.03.002, PII S004763740400048X
    • Weintraub SJ, Manson SR. Asparagine deamidation: a regulatory hourglass. Mech Ageing Dev. 2004;125:255-7. (Pubitemid 38438503)
    • (2004) Mechanisms of Ageing and Development , vol.125 , Issue.4 , pp. 255-257
    • Weintraub, S.J.1    Manson, S.R.2
  • 47
    • 67650482859 scopus 로고    scopus 로고
    • Identification and characterization of asparagine deamidation in the light chain CDR1 of a humanized IgG1 antibody
    • Vlasak J, Bussat M, Wang S, Wagner-Rousset E, Schaefer M, Klinguer-Hamour C, et al. Identification and characterization of asparagine deamidation in the light chain CDR1 of a humanized IgG1 antibody. Anal Biochem. 2009;392:145-54.
    • (2009) Anal Biochem , vol.392 , pp. 145-154
    • Vlasak, J.1    Bussat, M.2    Wang, S.3    Wagner-Rousset, E.4    Schaefer, M.5    Klinguer-Hamour, C.6
  • 48
    • 67649207267 scopus 로고    scopus 로고
    • Engineering human IgG1 affinity to human neonatal Fc receptor: Impact of affinity improvement on pharmacokinetics in primates
    • Yeung YA, Leabman MK, Marvin JS, Qiu J, Adams CW, Lien S, et al. Engineering human IgG1 affinity to human neonatal Fc receptor: impact of affinity improvement on pharmacokinetics in primates. J Immunol. 2009;182:7663-71.
    • (2009) J Immunol , vol.182 , pp. 7663-7671
    • Yeung, Y.A.1    Leabman, M.K.2    Marvin, J.S.3    Qiu, J.4    Adams, C.W.5    Lien, S.6
  • 50
    • 0033636448 scopus 로고    scopus 로고
    • Kinetic and thermodynamic control of the relative yield of the deamidation of asparagine and isomerization of aspartic acid residues
    • Capasso S, Di Cerbo P. Kinetic and thermodynamic control of the relative yield of the deamidation of asparagine and isomerization of aspartic acid residues. J Pept Res. 2000;56:382-7.
    • (2000) J Pept Res , vol.56 , pp. 382-387
    • Capasso, S.1    Di Cerbo, P.2


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