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Volumn 57, Issue 4, 2004, Pages 684-691

Relationship between local structural entropy and protein thermostability

Author keywords

Mesophilic proteins; Structural conservation; Structural entropy; Thermal stability; Thermophilic proteins

Indexed keywords

ADENYLATE KINASE; CYTOCHROME C; HOLOCYTOCHROME C 551; RIBONUCLEASE H; UNCLASSIFIED DRUG;

EID: 10344224512     PISSN: 08873585     EISSN: None     Source Type: Journal    
DOI: 10.1002/prot.20263     Document Type: Article
Times cited : (62)

References (50)
  • 1
    • 0027469674 scopus 로고
    • Thermal unfolding of staphylococcal nuclease and several mutant forms thereof studied by differential scanning calorimetry
    • Tanaka A, Flanagan J, Sturtevant JM. Thermal unfolding of staphylococcal nuclease and several mutant forms thereof studied by differential scanning calorimetry. Protein Sci 1993;2:567-76.
    • (1993) Protein Sci , vol.2 , pp. 567-576
    • Tanaka, A.1    Flanagan, J.2    Sturtevant, J.M.3
  • 2
    • 0028846686 scopus 로고
    • Crystal structure of recombinant triosephosphate isomerase from Bacillus stearothermophilus. An analysis of potential thermostability factors in six isomerases with known three-dimensional structures points to the importance of hydrophobic interactions
    • Delboni LF, Mande SC, Rentier-Delrue F, Mainfroid V, Turley S, Vellieux FM, Martial JA, Hol WG. Crystal structure of recombinant triosephosphate isomerase from Bacillus stearothermophilus. An analysis of potential thermostability factors in six isomerases with known three-dimensional structures points to the importance of hydrophobic interactions. Protein Sci 1995;4:2594-604.
    • (1995) Protein Sci , vol.4 , pp. 2594-2604
    • Delboni, L.F.1    Mande, S.C.2    Rentier-Delrue, F.3    Mainfroid, V.4    Turley, S.5    Vellieux, F.M.6    Martial, J.A.7    Hol, W.G.8
  • 3
    • 0030748521 scopus 로고    scopus 로고
    • The crystal structure of an Fe-superoxide dismutase from the hyperthermophile Aquifex pyrophilus at 1.9 Å resolution: Structural basis for thermostability
    • Lim JH, Yu YG, Han YS, Cho S, Ahn BY, Kim SH, Cho Y. The crystal structure of an Fe-superoxide dismutase from the hyperthermophile Aquifex pyrophilus at 1.9 Å resolution: structural basis for thermostability. J Mol Biol 1997;270:259-74.
    • (1997) J Mol Biol , vol.270 , pp. 259-274
    • Lim, J.H.1    Yu, Y.G.2    Han, Y.S.3    Cho, S.4    Ahn, B.Y.5    Kim, S.H.6    Cho, Y.7
  • 4
    • 0033010510 scopus 로고    scopus 로고
    • Crystal structures of thermostable xylose isomerases from Thermus caldophilus and Thermus thermophilus: Possible structural determinants of thermostability
    • Chang C, Park BC, Lee DS, Suh SW. Crystal structures of thermostable xylose isomerases from Thermus caldophilus and Thermus thermophilus: possible structural determinants of thermostability. J Mol Biol 1999;288:623-34.
    • (1999) J Mol Biol , vol.288 , pp. 623-634
    • Chang, C.1    Park, B.C.2    Lee, D.S.3    Suh, S.W.4
  • 5
    • 0033616712 scopus 로고    scopus 로고
    • Thermal adaptation analyzed by comparison of protein sequences from mesophilic and extremely thermophilic Methanococcus species
    • Haney PJ, Badger JH, Buldak GL, Reich CI, Woese CR, Olsen GJ. Thermal adaptation analyzed by comparison of protein sequences from mesophilic and extremely thermophilic Methanococcus species. Proc Natl Acad Sci USA 1999;96:3578-3583.
    • (1999) Proc Natl Acad Sci USA , vol.96 , pp. 3578-3583
    • Haney, P.J.1    Badger, J.H.2    Buldak, G.L.3    Reich, C.I.4    Woese, C.R.5    Olsen, G.J.6
  • 6
    • 0033621428 scopus 로고    scopus 로고
    • Stabilization of Pseudomonas aeruginosa cytochrome c(551) by systematic amino acid substitutions based on the structure of thermophilic Hydrogenobacter thermophilus cytochrome c(552)
    • Hasegawa J, Shimahara H, Mizutani M, Uchiyama S, Arai H, Ishii M, Kobayashi Y, Ferguson SJ, Sambongi Y, Igarashi Y. Stabilization of Pseudomonas aeruginosa cytochrome c(551) by systematic amino acid substitutions based on the structure of thermophilic Hydrogenobacter thermophilus cytochrome c(552). J Biol Chem 1999;274:37533-37537.
    • (1999) J Biol Chem , vol.274 , pp. 37533-37537
    • Hasegawa, J.1    Shimahara, H.2    Mizutani, M.3    Uchiyama, S.4    Arai, H.5    Ishii, M.6    Kobayashi, Y.7    Ferguson, S.J.8    Sambongi, Y.9    Igarashi, Y.10
  • 7
    • 0032737311 scopus 로고    scopus 로고
    • Patterns of temperature adaptation in proteins from Methanococcus and Bacillus
    • McDonald JH, Grasso AM, Rejto LK. Patterns of temperature adaptation in proteins from Methanococcus and Bacillus. Mol Biol Evol 1999;16:1785-1790.
    • (1999) Mol Biol Evol , vol.16 , pp. 1785-1790
    • McDonald, J.H.1    Grasso, A.M.2    Rejto, L.K.3
  • 8
    • 0034693042 scopus 로고    scopus 로고
    • Structural and genomic correlates of hyperthermostability
    • Cambillau C, Claverie JM. Structural and genomic correlates of hyperthermostability. J Biol Chem 2000;275:32383-6.
    • (2000) J Biol Chem , vol.275 , pp. 32383-32386
    • Cambillau, C.1    Claverie, J.M.2
  • 9
    • 0034191064 scopus 로고    scopus 로고
    • The stability of thermophilic proteins: A study based on comprehensive genome comparison
    • Das R, Gerstein M. The stability of thermophilic proteins: a study based on comprehensive genome comparison. Funct Integr Genomics 2000;1:76-88.
    • (2000) Funct Integr Genomics , vol.1 , pp. 76-88
    • Das, R.1    Gerstein, M.2
  • 10
    • 0034714134 scopus 로고    scopus 로고
    • Probing structural determinants specifying high thermostability in Bacillus licheniformis alpha-amylase
    • Declerck N, Machius M, Wiegand G, Huber R, Gaillardin C. Probing structural determinants specifying high thermostability in Bacillus licheniformis alpha-amylase. J Mol Biol 2000;301:1041-57.
    • (2000) J Mol Biol , vol.301 , pp. 1041-1057
    • Declerck, N.1    Machius, M.2    Wiegand, G.3    Huber, R.4    Gaillardin, C.5
  • 11
    • 0034017055 scopus 로고    scopus 로고
    • Factors enhancing protein thermostability
    • Kumar S, Tsai CJ, Nussinov R. Factors enhancing protein thermostability. Protein Eng 2000;13:179-91.
    • (2000) Protein Eng , vol.13 , pp. 179-191
    • Kumar, S.1    Tsai, C.J.2    Nussinov, R.3
  • 12
    • 0034100848 scopus 로고    scopus 로고
    • Two exposed amino acid residues confer thermostability on a cold shock protein
    • Perl D, Mueller U, Heinemann U, Schmid FX. Two exposed amino acid residues confer thermostability on a cold shock protein. Nat Struct Biol 2000;7:380-3.
    • (2000) Nat Struct Biol , vol.7 , pp. 380-383
    • Perl, D.1    Mueller, U.2    Heinemann, U.3    Schmid, F.X.4
  • 13
    • 0039116206 scopus 로고    scopus 로고
    • Structural differences between mesophilic, moderately thermophilic and extremely thermophilic protein subunits: Results of a comprehensive survey
    • Szilagyi A, Zavodszky P. Structural differences between mesophilic, moderately thermophilic and extremely thermophilic protein subunits: results of a comprehensive survey. Structure Fold Des 2000;8:493-504.
    • (2000) Structure Fold Des , vol.8 , pp. 493-504
    • Szilagyi, A.1    Zavodszky, P.2
  • 14
    • 0035312933 scopus 로고    scopus 로고
    • Identification of thermophilic species by the amino acid compositions deduced from their genomes
    • Kreil DP, Ouzounis CA. Identification of thermophilic species by the amino acid compositions deduced from their genomes. Nucleic Acids Res. 2001;29:1608-1615.
    • (2001) Nucleic Acids Res , vol.29 , pp. 1608-1615
    • Kreil, D.P.1    Ouzounis, C.A.2
  • 15
    • 20644438446 scopus 로고    scopus 로고
    • Protein folding and function: The N-terminal fragment in adenylate kinase
    • Kumar S, Sham YY, Tsai CJ, Nussinov R. Protein folding and function: the N-terminal fragment in adenylate kinase. Biophys J 2001;80:2439-54.
    • (2001) Biophys J , vol.80 , pp. 2439-2454
    • Kumar, S.1    Sham, Y.Y.2    Tsai, C.J.3    Nussinov, R.4
  • 16
    • 0035960641 scopus 로고    scopus 로고
    • Thermodynamic differences among homologous thermophilic and mesophilic proteins
    • Kumar S, Tsai CJ, Nussinov R. Thermodynamic differences among homologous thermophilic and mesophilic proteins. Biochemistry 2001;40:14152-65.
    • (2001) Biochemistry , vol.40 , pp. 14152-14165
    • Kumar, S.1    Tsai, C.J.2    Nussinov, R.3
  • 17
    • 0035424955 scopus 로고    scopus 로고
    • Engineering proteins for thermostability: The use of sequence alignments versus rational design and directed evolution
    • Lehmann M, Wyss M. Engineering proteins for thermostability: the use of sequence alignments versus rational design and directed evolution. Curr Opin Biotechnol 2001;12:371-5.
    • (2001) Curr Opin Biotechnol , vol.12 , pp. 371-375
    • Lehmann, M.1    Wyss, M.2
  • 18
    • 0035098779 scopus 로고    scopus 로고
    • Hyperthermophilic enzymes: Sources, uses, and molecular mechanisms for thermostability
    • Vieille C, Zeikus GJ. Hyperthermophilic enzymes: sources, uses, and molecular mechanisms for thermostability. Microbiol Mol Biol Rev 2001;65:1-43.
    • (2001) Microbiol Mol Biol Rev , vol.65 , pp. 1-43
    • Vieille, C.1    Zeikus, G.J.2
  • 19
    • 0037172796 scopus 로고    scopus 로고
    • Elucidation of factors responsible for enhanced thermal stability of proteins: A structural genomics based study
    • Chakravarty S, Varadarajan R. Elucidation of factors responsible for enhanced thermal stability of proteins: a structural genomics based study. Biochemistry 2002;41:8152-61.
    • (2002) Biochemistry , vol.41 , pp. 8152-8161
    • Chakravarty, S.1    Varadarajan, R.2
  • 20
    • 0036606927 scopus 로고    scopus 로고
    • Evidence for cysteine clustering in thermophilic proteomes
    • Rosato V, Pucello N, Giuliano G. Evidence for cysteine clustering in thermophilic proteomes. Trends Genet 2002;18:278-281.
    • (2002) Trends Genet , vol.18 , pp. 278-281
    • Rosato, V.1    Pucello, N.2    Giuliano, G.3
  • 21
    • 0038690122 scopus 로고    scopus 로고
    • Structures of thermophilic and mesophilic adenylate kinases from the genus Methanococcus
    • Criswell AR, Bae E, Stec B, Konisky J, Phillips GN, Jr. Structures of thermophilic and mesophilic adenylate kinases from the genus Methanococcus. J Mol Biol 2003;330:1087-99.
    • (2003) J Mol Biol , vol.330 , pp. 1087-1099
    • Criswell, A.R.1    Bae, E.2    Stec, B.3    Konisky, J.4    Phillips Jr., G.N.5
  • 22
    • 0042165863 scopus 로고    scopus 로고
    • Using motif-based methods in multiple genome analyses: A case study comparing orthologous mesophilic and thermophilic proteins
    • La D, Silver M, Edgar RC, Livesay DR. Using motif-based methods in multiple genome analyses: a case study comparing orthologous mesophilic and thermophilic proteins. Biochemistry 2003;42:8988-98.
    • (2003) Biochemistry , vol.42 , pp. 8988-8998
    • La, D.1    Silver, M.2    Edgar, R.C.3    Livesay, D.R.4
  • 23
    • 0037837789 scopus 로고    scopus 로고
    • Kinetic stabilization of Bacillus licheniformis alpha-amylase through introduction of hydrophobic residues at the surface
    • Machius M, Declerck N, Huber R, Wiegand G. Kinetic stabilization of Bacillus licheniformis alpha-amylase through introduction of hydrophobic residues at the surface. J Biol Chem 2003;278:11546-53.
    • (2003) J Biol Chem , vol.278 , pp. 11546-11553
    • Machius, M.1    Declerck, N.2    Huber, R.3    Wiegand, G.4
  • 24
    • 0037340834 scopus 로고    scopus 로고
    • Real value prediction of solvent accessibility from amino acid sequence
    • Ahmad S, Gromiha MM, Sarai A. Real value prediction of solvent accessibility from amino acid sequence. Proteins 2003;50:629-35.
    • (2003) Proteins , vol.50 , pp. 629-635
    • Ahmad, S.1    Gromiha, M.M.2    Sarai, A.3
  • 25
    • 0032773941 scopus 로고    scopus 로고
    • Role of structural and sequence information in the prediction of protein stability changes: Comparison between buried and partially buried mutations
    • Gromiha MM, Oobatake M, Kono H, Uedaira H, Sarai A. Role of structural and sequence information in the prediction of protein stability changes: comparison between buried and partially buried mutations. Protein Eng 1999;12:549-55.
    • (1999) Protein Eng , vol.12 , pp. 549-555
    • Gromiha, M.M.1    Oobatake, M.2    Kono, H.3    Uedaira, H.4    Sarai, A.5
  • 26
    • 0020997912 scopus 로고
    • Dictionary of protein secondary structure: Pattern recognition of hydrogen-bonded and geometrical features
    • Kabsch W, Sander C. Dictionary of protein secondary structure: pattern recognition of hydrogen-bonded and geometrical features. Biopolymers 1983;22:2577-2673.
    • (1983) Biopolymers , vol.22 , pp. 2577-2673
    • Kabsch, W.1    Sander, C.2
  • 27
    • 0028091659 scopus 로고
    • Detection of conserved segments in proteins: Iterative scanning of sequence databases with alignment blocks
    • Tatusov RL, Altschul SF, Koonin EV. Detection of conserved segments in proteins: iterative scanning of sequence databases with alignment blocks. Proc Natl Acad Sci USA 1994;91:12091-5.
    • (1994) Proc Natl Acad Sci USA , vol.91 , pp. 12091-12095
    • Tatusov, R.L.1    Altschul, S.F.2    Koonin, E.V.3
  • 28
    • 0033977581 scopus 로고    scopus 로고
    • The ASTRAL compendium for protein structure and sequence analysis
    • Brenner SE, Koehl P, Levitt M. The ASTRAL compendium for protein structure and sequence analysis. Nucleic Acids Research 2000;28:254-256.
    • (2000) Nucleic Acids Research , vol.28 , pp. 254-256
    • Brenner, S.E.1    Koehl, P.2    Levitt, M.3
  • 29
    • 0026069154 scopus 로고
    • Development of hydrophobicity parameters to analyze proteins which bear post- or cotranslational modifications
    • Black SD, Mould DR. Development of hydrophobicity parameters to analyze proteins which bear post- or cotranslational modifications. Anal Biochem 1991;193:72-82.
    • (1991) Anal Biochem , vol.193 , pp. 72-82
    • Black, S.D.1    Mould, D.R.2
  • 30
    • 0033214040 scopus 로고    scopus 로고
    • Analysis of thermal stabilizing interactions in mesophilic and thermophilic adenylate kinases from the genus Methanococcus
    • Haney PJ, Stees M, Konisky J. Analysis of thermal stabilizing interactions in mesophilic and thermophilic adenylate kinases from the genus Methanococcus. J Biol Chem 1999;274:28453-8.
    • (1999) J Biol Chem , vol.274 , pp. 28453-28458
    • Haney, P.J.1    Stees, M.2    Konisky, J.3
  • 31
    • 0026803109 scopus 로고
    • Stabilization of Escherichia coli ribonuclease HI by strategic replacement of amino acid residues with those from the thermophilic counterpart
    • Kimura S, Nakamura H, Hashimoto T, Oobatake M, Kanaya S. Stabilization of Escherichia coli ribonuclease HI by strategic replacement of amino acid residues with those from the thermophilic counterpart. J Biol Chem 1992;267:21535-42.
    • (1992) J Biol Chem , vol.267 , pp. 21535-21542
    • Kimura, S.1    Nakamura, H.2    Hashimoto, T.3    Oobatake, M.4    Kanaya, S.5
  • 33
    • 0033514919 scopus 로고    scopus 로고
    • Tolerance of Arc repressor to multiple-alanine substitutions
    • Brown BM, Sauer RT. Tolerance of Arc repressor to multiple-alanine substitutions. Proc Natl Acad Sci USA 1999;96:1983-8.
    • (1999) Proc Natl Acad Sci USA , vol.96 , pp. 1983-1988
    • Brown, B.M.1    Sauer, R.T.2
  • 34
    • 0034673153 scopus 로고    scopus 로고
    • Contribution of surface salt bridges to protein stability
    • Strop P, Mayo SL. Contribution of surface salt bridges to protein stability. Biochemistry 2000;39:1251-5.
    • (2000) Biochemistry , vol.39 , pp. 1251-1255
    • Strop, P.1    Mayo, S.L.2
  • 35
    • 0034691318 scopus 로고    scopus 로고
    • Thermodynamic characterization of mutants of human fibroblast growth factor 1 with an increased physiological half-life
    • Culajay JF, Blaber SI, Khurana A, Blaber M. Thermodynamic characterization of mutants of human fibroblast growth factor 1 with an increased physiological half-life. Biochemistry 2000;39:7153-8.
    • (2000) Biochemistry , vol.39 , pp. 7153-7158
    • Culajay, J.F.1    Blaber, S.I.2    Khurana, A.3    Blaber, M.4
  • 36
    • 0141596172 scopus 로고    scopus 로고
    • Structural and functional adaptations to extreme temperatures in psychrophilic, mesophilic, and thermophilic DNA ligases
    • Georlette D, Damien B, Biaise V, Depiereux E, Uversky VN, Gerday C, Feller G. Structural and functional adaptations to extreme temperatures in psychrophilic, mesophilic, and thermophilic DNA ligases. J Biol Chem 2003;278:37015-23.
    • (2003) J Biol Chem , vol.278 , pp. 37015-37023
    • Georlette, D.1    Damien, B.2    Biaise, V.3    Depiereux, E.4    Uversky, V.N.5    Gerday, C.6    Feller, G.7
  • 38
    • 0031837178 scopus 로고    scopus 로고
    • Enhanced thermal stability of Clostridium beijerinckii alcohol dehydrogenase after strategic substitution of amino acid residues with prolines from the homologous thermophilic Thermoanaerobacter brockii alcohol dehydrogenase
    • Bogin O, Peretz M, Hacham Y, Korkhin Y, Frolow F, Kalb AJ, Burstein Y. Enhanced thermal stability of Clostridium beijerinckii alcohol dehydrogenase after strategic substitution of amino acid residues with prolines from the homologous thermophilic Thermoanaerobacter brockii alcohol dehydrogenase. Protein Sci 1998;7:1156-63.
    • (1998) Protein Sci , vol.7 , pp. 1156-1163
    • Bogin, O.1    Peretz, M.2    Hacham, Y.3    Korkhin, Y.4    Frolow, F.5    Kalb, A.J.6    Burstein, Y.7
  • 39
    • 0032493739 scopus 로고    scopus 로고
    • Investigation of the structural basis for thermostability of DNA-binding protein HU from Bacillus stearothermophilus
    • Kawamura S, Abe Y, Ueda T, Masumoto K, Imoto T, Yamasaki N, Kimura M. Investigation of the structural basis for thermostability of DNA-binding protein HU from Bacillus stearothermophilus. J Biol Chem 1998;273:19982-7.
    • (1998) J Biol Chem , vol.273 , pp. 19982-19987
    • Kawamura, S.1    Abe, Y.2    Ueda, T.3    Masumoto, K.4    Imoto, T.5    Yamasaki, N.6    Kimura, M.7
  • 40
    • 0036172116 scopus 로고    scopus 로고
    • Hydrophobic core packing in the SH3 domain folding transition state
    • Northey JG, Di Nardo AA, Davidson AR. Hydrophobic core packing in the SH3 domain folding transition state. Nat Struct Biol 2002;9:126-30.
    • (2002) Nat Struct Biol , vol.9 , pp. 126-130
    • Northey, J.G.1    Di Nardo, A.A.2    Davidson, A.R.3
  • 41
    • 0036310988 scopus 로고    scopus 로고
    • Origins of the high stability of an in vitro-selected cold-shock protein
    • Martin A, Kather I, Schmid FX. Origins of the high stability of an in vitro-selected cold-shock protein. J Mol Biol 2002;318:1341-9.
    • (2002) J Mol Biol , vol.318 , pp. 1341-1349
    • Martin, A.1    Kather, I.2    Schmid, F.X.3
  • 43
    • 0347927627 scopus 로고    scopus 로고
    • Preliminary characterization and crystal structure of a thermostable cytochrome P450 from Thermus thermophilus
    • Yano JK, Blasco F, Li H, Schmid RD, Henne A, Poulos TL. Preliminary characterization and crystal structure of a thermostable cytochrome P450 from Thermus thermophilus. J Biol Chem 2003;278:608-16.
    • (2003) J Biol Chem , vol.278 , pp. 608-616
    • Yano, J.K.1    Blasco, F.2    Li, H.3    Schmid, R.D.4    Henne, A.5    Poulos, T.L.6
  • 44
    • 0034976980 scopus 로고    scopus 로고
    • Increasing protein stability using a rational approach combining sequence homology and structural alignment: Stabilizing the WW domain
    • Jiang X, Kowalski J, Kelly JW. Increasing protein stability using a rational approach combining sequence homology and structural alignment: Stabilizing the WW domain. Protein Sci 2001;10:1454-65.
    • (2001) Protein Sci , vol.10 , pp. 1454-1465
    • Jiang, X.1    Kowalski, J.2    Kelly, J.W.3
  • 45
    • 0029018778 scopus 로고
    • Contribution of individual side-chains to the stability of BPTI examined by alanine-scanning mutagenesis
    • Yu MH, Weissman JS, Kim PS. Contribution of individual side-chains to the stability of BPTI examined by alanine-scanning mutagenesis. J Mol Biol 1995;249:388-97.
    • (1995) J Mol Biol , vol.249 , pp. 388-397
    • Yu, M.H.1    Weissman, J.S.2    Kim, P.S.3
  • 46
    • 0034607555 scopus 로고    scopus 로고
    • Folding of bovine pancreatic trypsin inhibitor (BPTI) variants in which almost half the residues are alanine
    • Kuroda Y, Kim PS. Folding of bovine pancreatic trypsin inhibitor (BPTI) variants in which almost half the residues are alanine. J Mol Biol 2000;298:493-501.
    • (2000) J Mol Biol , vol.298 , pp. 493-501
    • Kuroda, Y.1    Kim, P.S.2
  • 47
    • 0035936616 scopus 로고    scopus 로고
    • Structure-based chimeric enzymes as an alternative to directed enzyme evolution: Phytase as a test case
    • Jermutus L, Tessier M, Pasamontes L, van Loon AP, Lehmann M. Structure-based chimeric enzymes as an alternative to directed enzyme evolution: phytase as a test case. J Biotechnol 2001;85:15-24.
    • (2001) J Biotechnol , vol.85 , pp. 15-24
    • Jermutus, L.1    Tessier, M.2    Pasamontes, L.3    Van Loon, A.P.4    Lehmann, M.5
  • 49
    • 0032482955 scopus 로고    scopus 로고
    • An entropy criterion to detect minimally frustrated intermediates in native proteins
    • Compiani M, Fariselli P, Martelli PL, Casadio R. An entropy criterion to detect minimally frustrated intermediates in native proteins. Proc Natl Acad Sci USA 1998;95:9290-4.
    • (1998) Proc Natl Acad Sci USA , vol.95 , pp. 9290-9294
    • Compiani, M.1    Fariselli, P.2    Martelli, P.L.3    Casadio, R.4


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