Skip to main content

Advertisement

Log in

Structural dynamics of native and V260E mutant C-terminal domain of HIV-1 integrase

  • Published:
Journal of Computer-Aided Molecular Design Aims and scope Submit manuscript

Abstract

The C-terminal domain (CTD) of HIV-1 integrase is a five stranded β-barrel resembling an SH3 fold. Mutational studies on isolated CTD and full-length IN have reported V260E mutant as either homo-dimerization defective or affecting the stability and folding of CTD. In this study, molecular dynamics simulation techniques were used to unveil the effect of V260E mutation on isolated CTD monomer and dimer. Both monomeric and dimeric forms of wild type and V260E mutant are highly stable during the simulated period. However, the stabilizing π-stacking interaction between Trp243 and Trp243′ at the dimer interface is highly disturbed in CTD-V260E (>6 Å apart). The loss in entropy for dimerization is −30 and −25 kcal/mol for CTD-wt and CTD-V260E respectively signifying a weak hydrophobic interaction and its perturbation in CTD-V260E. The mutant Glu260 exhibits strong attraction/repulsion with all the basic/acidic residues of CTD. In addition to this, the dynamics of CTD-wild type and V260E monomers at 498 K was analyzed to elucidate the effect of V260E mutation on CTD folding. Increase in SASA and reduction in the number of contacts in CTD-V260E during simulation highlights the instability caused by the mutation. In general, V260E mutation affects both multimerization and protein folding with a pronounced effect on protein folding rather than multimerization. This study emphasizes the importance of the hydrophobic nature and SH3 fold of CTD in proper functioning of HIV integrase and perturbing this nature would be a rational approach toward designing more selective and potent allosteric anti-HIV inhibitors.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10

Similar content being viewed by others

References

  1. Chen H, Engelman A (2001) Asymmetric processing of human immunodeficiency virus type 1 cDNA in vivo: implications for functional end coupling during the chemical steps of DNA transposition. Mol Cell Biol 21(20):6758–6767. doi:10.1128/MCB.21.20.6758-6767.2001

    Article  CAS  Google Scholar 

  2. Guiot E, Carayon K, Delelis O, Simon F, Tauc P, Zubin E, Gottikh M, Mouscadet JF, Brochon JC, Deprez E (2006) Relationship between the oligomeric status of HIV-1 integrase on DNA and enzymatic activity. J Biol Chem 281(32):22707–22719. doi:10.1074/jbc.M602198200

    Article  CAS  Google Scholar 

  3. Sherman PA, Fyfe JA (1990) Human immunodeficiency virus integration protein expressed in Escherichia coli possesses selective DNA cleaving activity. Proc Natl Acad Sci USA 87(13):5119–5123

    Article  CAS  Google Scholar 

  4. Vink C, Yeheskiely E, van der Marel GA, van Boom JH, Plasterk RH (1991) Site-specific hydrolysis and alcoholysis of human immunodeficiency virus DNA termini mediated by the viral integrase protein. Nucleic Acids Res 19(24):6691–6698

    Article  CAS  Google Scholar 

  5. Wei SQ, Mizuuchi K, Craigie R (1997) A large nucleoprotein assembly at the ends of the viral DNA mediates retroviral DNA integration. EMBO J 16(24):7511–7520. doi:10.1093/emboj/16.24.7511

    Article  CAS  Google Scholar 

  6. Engelman A, Mizuuchi K, Craigie R (1991) HIV-1 DNA integration: mechanism of viral DNA cleavage and DNA strand transfer. Cell 67(6):1211–1221

    Article  CAS  Google Scholar 

  7. Bushman FD, Craigie R (1991) Activities of human immunodeficiency virus (HIV) integration protein in vitro: specific cleavage and integration of HIV DNA. Proc Natl Acad Sci USA 88(4):1339–1343

    Article  CAS  Google Scholar 

  8. Bushman FD, Fujiwara T, Craigie R (1990) Retroviral DNA integration directed by HIV integration protein in vitro. Science 249(4976):1555–1558

    Article  CAS  Google Scholar 

  9. Delelis O, Carayon K, Saib A, Deprez E, Mouscadet JF (2008) Integrase and integration: biochemical activities of HIV-1 integrase. Retrovirology 5:114. doi:10.1186/1742-4690-5-114

    Article  Google Scholar 

  10. Muller HP, Varmus HE (1994) DNA bending creates favored sites for retroviral integration: an explanation for preferred insertion sites in nucleosomes. EMBO J 13(19):4704–4714

    CAS  Google Scholar 

  11. Bushman FD, Engelman A, Palmer I, Wingfield P, Craigie R (1993) Domains of the integrase protein of human immunodeficiency virus type 1 responsible for polynucleotidyl transfer and zinc binding. Proc Natl Acad Sci USA 90(8):3428–3432

    Article  CAS  Google Scholar 

  12. Engelman A, Bushman FD, Craigie R (1993) Identification of discrete functional domains of HIV-1 integrase and their organization within an active multimeric complex. EMBO J 12(8):3269–3275

    CAS  Google Scholar 

  13. Engelman A, Craigie R (1992) Identification of conserved amino acid residues critical for human immunodeficiency virus type 1 integrase function in vitro. J Virol 66(11):6361–6369

    CAS  Google Scholar 

  14. van Gent DC, Vink C, Groeneger AA, Plasterk RH (1993) Complementation between HIV integrase proteins mutated in different domains. EMBO J 12(8):3261–3267

    Google Scholar 

  15. Cai M, Zheng R, Caffrey M, Craigie R, Clore GM, Gronenborn AM (1997) Solution structure of the N-terminal zinc binding domain of HIV-1 integrase. Nat Struct Biol 4(7):567–577

    Article  CAS  Google Scholar 

  16. Lodi PJ, Ernst JA, Kuszewski J, Hickman AB, Engelman A, Craigie R, Clore GM, Gronenborn AM (1995) Solution structure of the DNA binding domain of HIV-1 integrase. Biochemistry 34(31):9826–9833

    Article  CAS  Google Scholar 

  17. Zheng R, Jenkins TM, Craigie R (1996) Zinc folds the N-terminal domain of HIV-1 integrase, promotes multimerization, and enhances catalytic activity. Proc Natl Acad Sci USA 93(24):13659–13664

    Article  CAS  Google Scholar 

  18. Goldgur Y, Dyda F, Hickman AB, Jenkins TM, Craigie R, Davies DR (1998) Three new structures of the core domain of HIV-1 integrase: an active site that binds magnesium. Proc Natl Acad Sci USA 95(16):9150–9154

    Article  CAS  Google Scholar 

  19. Maignan S, Guilloteau JP, Zhou-Liu Q, Clement-Mella C, Mikol V (1998) Crystal structures of the catalytic domain of HIV-1 integrase free and complexed with its metal cofactor: high level of similarity of the active site with other viral integrases. J Mol Biol 282(2):359–368. doi:10.1006/jmbi.1998.2002

    Article  CAS  Google Scholar 

  20. Engelman A, Hickman AB, Craigie R (1994) The core and carboxyl-terminal domains of the integrase protein of human immunodeficiency virus type 1 each contribute to nonspecific DNA binding. J Virol 68(9):5911–5917

    CAS  Google Scholar 

  21. Woerner AM, Klutch M, Levin JG, Marcus-Sekura CJ (1992) Localization of DNA binding activity of HIV-1 integrase to the C-terminal half of the protein. AIDS Res Hum Retroviruses 8(2):297–304

    Article  CAS  Google Scholar 

  22. Jaskolski M, Alexandratos JN, Bujacz G, Wlodawer A (2009) Piecing together the structure of retroviral integrase, an important target in AIDS therapy. FEBS J 276(11):2926–2946. doi:10.1111/j.1742-4658.2009.07009.x

    Article  CAS  Google Scholar 

  23. Wang JY, Ling H, Yang W, Craigie R (2001) Structure of a two-domain fragment of HIV-1 integrase: implications for domain organization in the intact protein. EMBO J 20(24):7333–7343. doi:10.1093/emboj/20.24.7333

    Article  CAS  Google Scholar 

  24. Chen JC, Krucinski J, Miercke LJ, Finer-Moore JS, Tang AH, Leavitt AD, Stroud RM (2000) Crystal structure of the HIV-1 integrase catalytic core and C-terminal domains: a model for viral DNA binding. Proc Natl Acad Sci USA 97(15):8233–8238. doi:10.1073/pnas.150220297

    Article  CAS  Google Scholar 

  25. Balasubramanian S, Rajagopalan M, Ramaswamy A (2012) Structural dynamics of full-length retroviral integrase: a molecular dynamics analysis. J Biomol Struct Dyn 29(6):659–670. doi:10.1080/07391102.2011.672630

    Article  Google Scholar 

  26. Heuer TS, Brown PO (1998) Photo-cross-linking studies suggest a model for the architecture of an active human immunodeficiency virus type 1 integrase-DNA complex. Biochemistry 37(19):6667–6678. doi:10.1021/bi972949c

    Article  CAS  Google Scholar 

  27. Karki RG, Tang Y, Burke TR Jr, Nicklaus MC (2004) Model of full-length HIV-1 integrase complexed with viral DNA as template for anti-HIV drug design. J Comput Aided Mol Des 18(12):739–760. doi:10.1007/s10822-005-0365-5

    Article  CAS  Google Scholar 

  28. Krishnan L, Li X, Naraharisetty HL, Hare S, Cherepanov P, Engelman A (2010) Structure-based modeling of the functional HIV-1 intasome and its inhibition. Proc Natl Acad Sci USA 107(36):15910–15915. doi:10.1073/pnas.1002346107

    Article  CAS  Google Scholar 

  29. Podtelezhnikov AA, Gao K, Bushman FD, McCammon JA (2003) Modeling HIV-1 integrase complexes based on their hydrodynamic properties. Biopolymers 68(1):110–120. doi:10.1002/bip.10217

    Article  CAS  Google Scholar 

  30. Wielens J, Crosby IT, Chalmers DK (2005) A three-dimensional model of the human immunodeficiency virus type 1 integration complex. J Comput Aided Mol Des 19(5):301–317. doi:10.1007/s10822-005-5256-2

    Article  CAS  Google Scholar 

  31. Hare S, Gupta SS, Valkov E, Engelman A, Cherepanov P (2010) Retroviral intasome assembly and inhibition of DNA strand transfer. Nature 464(7286):232–236. doi:10.1038/nature08784

    Article  CAS  Google Scholar 

  32. Bojja RS, Andrake MD, Weigand S, Merkel G, Yarychkivska O, Henderson A, Kummerling M, Skalka AM (2011) Architecture of a full-length retroviral integrase monomer and dimer, revealed by small angle X-ray scattering and chemical cross-linking. J Biol Chem 286(19):17047–17059. doi:10.1074/jbc.M110.212571

    Article  CAS  Google Scholar 

  33. Bojja RS, Andrake MD, Merkel G, Weigand S, Dunbrack RL Jr, Skalka AM (2013) Architecture and assembly of HIV integrase multimers in the absence of DNA substrates. J Biol Chem 288(10):7373–7386. doi:10.1074/jbc.M112.434431

    Article  CAS  Google Scholar 

  34. Zhao Z, McKee CJ, Kessl JJ, Santos WL, Daigle JE, Engelman A, Verdine G, Kvaratskhelia M (2008) Subunit-specific protein footprinting reveals significant structural rearrangements and a role for N-terminal Lys-14 of HIV-1 integrase during viral DNA binding. J Biol Chem 283(9):5632–5641. doi:10.1074/jbc.M705241200

    Article  CAS  Google Scholar 

  35. Engelman A (1999) In vivo analysis of retroviral integrase structure and function. Adv Virus Res 52:411–426

    Article  CAS  Google Scholar 

  36. Shin CG, Taddeo B, Haseltine WA, Farnet CM (1994) Genetic analysis of the human immunodeficiency virus type 1 integrase protein. J Virol 68(3):1633–1642

    CAS  Google Scholar 

  37. Taddeo B, Haseltine WA, Farnet CM (1994) Integrase mutants of human immunodeficiency virus type 1 with a specific defect in integration. J Virol 68(12):8401–8405

    CAS  Google Scholar 

  38. Lee SP, Xiao J, Knutson JR, Lewis MS, Han MK (1997) Zn2+ promotes the self-association of human immunodeficiency virus type-1 integrase in vitro. Biochemistry 36(1):173–180. doi:10.1021/bi961849o

    Article  CAS  Google Scholar 

  39. Engelman A, Englund G, Orenstein JM, Martin MA, Craigie R (1995) Multiple effects of mutations in human immunodeficiency virus type 1 integrase on viral replication. J Virol 69(5):2729–2736

    CAS  Google Scholar 

  40. Nakamura T, Masuda T, Goto T, Sano K, Nakai M, Harada S (1997) Lack of infectivity of HIV-1 integrase zinc finger-like domain mutant with morphologically normal maturation. Biochem Biophys Res Commun 239(3):715–722. doi:10.1006/bbrc.1997.7541

    Article  CAS  Google Scholar 

  41. Wu XY, Liu HM, Xiao HL, Conway JA, Hehl E, Kalpana GV, Prasad V, Kappes JC (1999) Human immunodeficiency virus type 1 integrase protein promotes reverse transcription through specific interactions with the nucleoprotein reverse transcription complex. J Virol 73(3):2126–2135

    CAS  Google Scholar 

  42. Leavitt AD, Robles G, Alesandro N, Varmus HE (1996) Human immunodeficiency virus type 1 integrase mutants retain in vitro integrase activity yet fail to integrate viral DNA efficiently during infection. J Virol 70(2):721–728

    CAS  Google Scholar 

  43. Masuda T, Planelles V, Krogstad P, Chen IS (1995) Genetic analysis of human immunodeficiency virus type 1 integrase and the U3 att site: unusual phenotype of mutants in the zinc finger-like domain. J Virol 69(11):6687–6696

    CAS  Google Scholar 

  44. Engelman A (2011) Pleiotropic nature of HIV-1 integrase mutations. In: Neamati N (ed) HIV-1 INTEGRASE: mechanism and inhibitor design. Wiley, Hoboken

    Google Scholar 

  45. Eijkelenboom AP, Lutzke RA, Boelens R, Plasterk RH, Kaptein R, Hard K (1995) The DNA-binding domain of HIV-1 integrase has an SH3-like fold. Nat Struct Biol 2(9):807–810

    Article  CAS  Google Scholar 

  46. Eijkelenboom AP, Sprangers R, Hard K, Puras Lutzke RA, Plasterk RH, Boelens R, Kaptein R (1999) Refined solution structure of the C-terminal DNA-binding domain of human immunovirus-1 integrase. Proteins 36(4):556–564. doi:10.1002/(SICI)1097-0134(19990901)36:4<556:AID-PROT18>3.0.CO;2-6

    Article  CAS  Google Scholar 

  47. Dar MJ, Monel B, Krishnan L, Shun MC, Di Nunzio F, Helland DE, Engelman A (2009) Biochemical and virological analysis of the 18-residue C-terminal tail of HIV-1 integrase. Retrovirology 6:94. doi:10.1186/1742-4690-6-94

    Article  Google Scholar 

  48. Mohammed KD, Topper MB, Muesing MA (2011) Sequential deletion of the integrase (Gag-Pol) carboxyl terminus reveals distinct phenotypic classes of defective HIV-1. J Virol 85(10):4654–4666. doi:10.1128/JVI.02374-10

    Article  CAS  Google Scholar 

  49. Mayer BJ, Eck MJ (1995) SH3 domains. Minding your p’s and q’s. Curr Biol 5(4):364–367

    Article  CAS  Google Scholar 

  50. Hehl EA, Joshi P, Kalpana GV, Prasad VR (2004) Interaction between human immunodeficiency virus type 1 reverse transcriptase and integrase proteins. J Virol 78(10):5056–5067

    Article  CAS  Google Scholar 

  51. Zhu K, Dobard C, Chow SA (2004) Requirement for integrase during reverse transcription of human immunodeficiency virus type 1 and the effect of cysteine mutations of integrase on its interactions with reverse transcriptase. J Virol 78(10):5045–5055

    Article  CAS  Google Scholar 

  52. Dirac AM, Kjems J (2001) Mapping DNA-binding sites of HIV-1 integrase by protein footprinting. Eur J Biochem 268(3):743–751

    Article  CAS  Google Scholar 

  53. Gao K, Butler SL, Bushman F (2001) Human immunodeficiency virus type 1 integrase: arrangement of protein domains in active cDNA complexes. EMBO J 20(13):3565–3576. doi:10.1093/emboj/20.13.3565

    Article  CAS  Google Scholar 

  54. Lutzke RA, Plasterk RH (1998) Structure-based mutational analysis of the C-terminal DNA-binding domain of human immunodeficiency virus type 1 integrase: critical residues for protein oligomerization and DNA binding. J Virol 72(6):4841–4848

    CAS  Google Scholar 

  55. Lutzke RA, Vink C, Plasterk RH (1994) Characterization of the minimal DNA-binding domain of the HIV integrase protein. Nucleic Acids Res 22(20):4125–4131

    Article  CAS  Google Scholar 

  56. Kalpana GV, Reicin A, Cheng GS, Sorin M, Paik S, Goff SP (1999) Isolation and characterization of an oligomerization-negative mutant of HIV-1 integrase. Virology 259(2):274–285. doi:10.1006/viro.1999.9767

    Article  CAS  Google Scholar 

  57. Ishikawa T, Okui N, Kobayashi N, Sakuma R, Kitamura T, Kitamura Y (1999) Monoclonal antibodies against the minimal DNA-binding domain in the carboxyl-terminal region of human immunodeficiency virus type 1 integrase. J Virol 73(5):4475–4480

    CAS  Google Scholar 

  58. Ceccherini-Silberstein F, Malet I, D’Arrigo R, Antinori A, Marcelin AG, Perno CF (2009) Characterization and structural analysis of HIV-1 integrase conservation. AIDS Rev 11(1):17–29

    Google Scholar 

  59. Hornak V, Okur A, Rizzo RC, Simmerling C (2006) HIV-1 protease flaps spontaneously open and reclose in molecular dynamics simulations. Proc Natl Acad Sci USA 103(4):915–920. doi:10.1073/pnas.0508452103

    Article  CAS  Google Scholar 

  60. Kim JH, Hartley TL, Curran AR, Engelman DM (2009) Molecular dynamics studies of the transmembrane domain of gp41 from HIV-1. Biochim Biophys Acta 1788(9):1804–1812. doi:10.1016/j.bbamem.2009.06.011

    Article  CAS  Google Scholar 

  61. Lins RD, Briggs JM, Straatsma TP, Carlson HA, Greenwald J, Choe S, McCammon JA (1999) Molecular dynamics studies on the HIV-1 integrase catalytic domain. Biophys J 76(6):2999–3011

    Article  CAS  Google Scholar 

  62. Madrid M, Jacobo-Molina A, Ding J, Arnold E (1999) Major subdomain rearrangement in HIV-1 reverse transcriptase simulated by molecular dynamics. Proteins 35(3):332–337. doi:10.1002/(SICI)1097-0134(19990515)35:3<332:AID-PROT7>3.0.CO;2-R

    Article  CAS  Google Scholar 

  63. Sangeetha B, Muthukumaran R, Amutha R (2014) The dynamics of interconverting D- and E-forms of the HIV-1 integrase N-terminal domain. Eur Biophys J 43(10–11):485–498. doi:10.1007/s00249-014-0979-4

    Article  CAS  Google Scholar 

  64. Barreca ML, Lee KW, Chimirri A, Briggs JM (2003) Molecular dynamics studies of the wild-type and double mutant HIV-1 integrase complexed with the 5CITEP inhibitor: mechanism for inhibition and drug resistance. Biophys J 84(3):1450–1463. doi:10.1016/S0006-3495(03)74958-3

    Article  CAS  Google Scholar 

  65. Brigo A, Lee KW, Fogolari F, Mustata GI, Briggs JM (2005) Comparative molecular dynamics simulations of HIV-1 integrase and the T66I/M154I mutant: binding modes and drug resistance to a diketo acid inhibitor. Proteins 59(4):723–741. doi:10.1002/prot.20447

    Article  CAS  Google Scholar 

  66. Li A, Daggett V (1994) Characterization of the transition state of protein unfolding by use of molecular dynamics: chymotrypsin inhibitor 2. Proc Natl Acad Sci USA 91(22):10430–10434

    Article  CAS  Google Scholar 

  67. Mayor U, Guydosh NR, Johnson CM, Grossmann JG, Sato S, Jas GS, Freund SM, Alonso DO, Daggett V, Fersht AR (2003) The complete folding pathway of a protein from nanoseconds to microseconds. Nature 421(6925):863–867. doi:10.1038/nature01428

    Article  CAS  Google Scholar 

  68. Alonso DO, Alm E, Daggett V (2000) Characterization of the unfolding pathway of the cell-cycle protein p13suc1 by molecular dynamics simulations: implications for domain swapping. Structure 8(1):101–110

    Article  CAS  Google Scholar 

  69. Kazmirski SL, Daggett V (1998) Non-native interactions in protein folding intermediates: molecular dynamics simulations of hen lysozyme. J Mol Biol 284(3):793–806. doi:10.1006/jmbi.1998.2192

    Article  CAS  Google Scholar 

  70. Alonso DO, Daggett V (1998) Molecular dynamics simulations of hydrophobic collapse of ubiquitin. Protein Sci 7(4):860–874. doi:10.1002/pro.5560070404

    Article  CAS  Google Scholar 

  71. Gu W, Wang T, Zhu J, Shi Y, Liu H (2003) Molecular dynamics simulation of the unfolding of the human prion protein domain under low pH and high temperature conditions. Biophys Chem 104(1):79–94

    Article  CAS  Google Scholar 

  72. Kazmirski SL, Daggett V (1998) Simulations of the structural and dynamical properties of denatured proteins: the “molten coil” state of bovine pancreatic trypsin inhibitor. J Mol Biol 277(2):487–506. doi:10.1006/jmbi.1998.1634

    Article  CAS  Google Scholar 

  73. Case DA, Darden TA, Cheatham TE, Simmerling CL, Wang J, Duke RE, Luo R, Walker RC, Zhang W, Merz KM, Roberts B, Wang B, Hayik S, Roitberg A, Seabra G, Kolossváry I, Wong KF, Paesani F, Vanicek J, Liu J, Wu X, Brozell SR, Steinbrecher T, Gohlke H, Cai Q, Ye X, Wang J, Hsieh M-J, Cui G, Roe DR, Mathews DH, Seetin MG, Sagui C, Babin V, Luchko T, Gusarov S, Kovalenko A, Kollman PA (2010) AMBER 11. University of California, San Francisco

    Google Scholar 

  74. Hornak V, Abel R, Okur A, Strockbine B, Roitberg A, Simmerling C (2006) Comparison of multiple Amber force fields and development of improved protein backbone parameters. Proteins 65(3):712–725. doi:10.1002/prot.21123

    Article  CAS  Google Scholar 

  75. Jorgensen WL, Chandrasekhar J, Madura JD, Impey RW, Klein ML (1983) Comparison of simple potential functions for simulating liquid water. J Chem Phys 79(2):926–935. doi:10.1063/1.445869

    Article  CAS  Google Scholar 

  76. Schreiner E, Trabuco LG, Freddolino PL, Schulten K (2011) Stereochemical errors and their implications for molecular dynamics simulations. BMC Bioinformatics 12:190. doi:10.1186/1471-2105-12-190

    Article  Google Scholar 

  77. Miller BR, McGee TD, Swails JM, Homeyer N, Gohlke H, Roitberg AE (2012) MMPBSA.py: an efficient program for end-state free energy calculations. J Chem Theory Comput 8(9):3314–3321. doi:10.1021/ct300418h

    Article  CAS  Google Scholar 

Download references

Acknowledgments

One of the Authors, Balasubramanian Sangeetha acknowledges the Department of Science and Technology, India for providing financial support through INSPIRE fellowship. Ramaswamy Amutha acknowledges Science and Engineering Research Board, India for providing computational facilities in the form of Fast Track Research Project for Young Scientists.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Ramaswamy Amutha.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Sangeetha, B., Muthukumaran, R. & Amutha, R. Structural dynamics of native and V260E mutant C-terminal domain of HIV-1 integrase. J Comput Aided Mol Des 29, 371–385 (2015). https://doi.org/10.1007/s10822-015-9830-y

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10822-015-9830-y

Keywords

Navigation