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Jin X, Zhu T, Zhang JZH, He X. Automated Fragmentation QM/MM Calculation of NMR Chemical Shifts for Protein-Ligand Complexes. Front Chem 2018; 6:150. [PMID: 29868556 PMCID: PMC5952040 DOI: 10.3389/fchem.2018.00150] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/16/2018] [Indexed: 01/13/2023] Open
Abstract
In this study, the automated fragmentation quantum mechanics/molecular mechanics (AF-QM/MM) method was applied for NMR chemical shift calculations of protein-ligand complexes. In the AF-QM/MM approach, the protein binding pocket is automatically divided into capped fragments (within ~200 atoms) for density functional theory (DFT) calculations of NMR chemical shifts. Meanwhile, the solvent effect was also included using the Poission-Boltzmann (PB) model, which properly accounts for the electrostatic polarization effect from the solvent for protein-ligand complexes. The NMR chemical shifts of neocarzinostatin (NCS)-chromophore binding complex calculated by AF-QM/MM accurately reproduce the large-sized system results. The 1H chemical shift perturbations (CSP) between apo-NCS and holo-NCS predicted by AF-QM/MM are also in excellent agreement with experimental results. Furthermore, the DFT calculated chemical shifts of the chromophore and residues in the NCS binding pocket can be utilized as molecular probes to identify the correct ligand binding conformation. By combining the CSP of the atoms in the binding pocket with the Glide scoring function, the new scoring function can accurately distinguish the native ligand pose from decoy structures. Therefore, the AF-QM/MM approach provides an accurate and efficient platform for protein-ligand binding structure prediction based on NMR derived information.
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Affiliation(s)
- Xinsheng Jin
- State Key Laboratory of Precision Spectroscopy, School of Chemistry and Molecular Engineering, Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai, China
| | - Tong Zhu
- State Key Laboratory of Precision Spectroscopy, School of Chemistry and Molecular Engineering, Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai, China
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai, China
| | - John Z. H. Zhang
- State Key Laboratory of Precision Spectroscopy, School of Chemistry and Molecular Engineering, Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai, China
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai, China
- Department of Chemistry, New York University, New York, NY, United States
| | - Xiao He
- State Key Laboratory of Precision Spectroscopy, School of Chemistry and Molecular Engineering, Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai, China
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai, China
- National Engineering Research Centre for Nanotechnology, Shanghai, China
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Li M, Zhang JZ, Xia F. Constructing Optimal Coarse-Grained Sites of Huge Biomolecules by Fluctuation Maximization. J Chem Theory Comput 2016; 12:2091-100. [PMID: 26930392 DOI: 10.1021/acs.jctc.6b00016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Coarse-grained (CG) models are valuable tools for the study of functions of large biomolecules on large length and time scales. The definition of CG representations for huge biomolecules is always a formidable challenge. In this work, we propose a new method called fluctuation maximization coarse-graining (FM-CG) to construct the CG sites of biomolecules. The defined residual in FM-CG converges to a maximal value as the number of CG sites increases, allowing an optimal CG model to be rigorously defined on the basis of the maximum. More importantly, we developed a robust algorithm called stepwise local iterative optimization (SLIO) to accelerate the process of coarse-graining large biomolecules. By means of the efficient SLIO algorithm, the computational cost of coarse-graining large biomolecules is reduced to within the time scale of seconds, which is far lower than that of conventional simulated annealing. The coarse-graining of two huge systems, chaperonin GroEL and lengsin, indicates that our new methods can coarse-grain huge biomolecular systems with up to 10,000 residues within the time scale of minutes. The further parametrization of CG sites derived from FM-CG allows us to construct the corresponding CG models for studies of the functions of huge biomolecular systems.
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Affiliation(s)
- Min Li
- School of Chemistry and Molecular Engineering, East China Normal University , Shanghai 200062, China.,State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University , Shanghai 200062, China
| | - John Zenghui Zhang
- State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University , Shanghai 200062, China.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai , Shanghai 200062, China
| | - Fei Xia
- School of Chemistry and Molecular Engineering, East China Normal University , Shanghai 200062, China.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai , Shanghai 200062, China
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Construction of a genetically engineered chimeric apoprotein consisting of sequences derived from lidamycin and neocarzinostatin. Anticancer Drugs 2016; 27:24-8. [DOI: 10.1097/cad.0000000000000300] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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4
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Probing the biophysical interaction between Neocarzinostatin toxin and EpCAM RNA aptamer. Biochem Biophys Res Commun 2015; 469:257-62. [PMID: 26642954 DOI: 10.1016/j.bbrc.2015.11.109] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 11/24/2015] [Indexed: 11/23/2022]
Abstract
Neocarzinostatin (NCS) a potent DNA-damaging, anti-tumor toxin extracted from Streptomyces carzinostaticus that recognizes double-stranded DNA bulge and induces DNA damage. 2 Fluoro (2F) Modified EpCAM RNA aptamer is a 23-mer that targets EpCAM protein, expressed on the surface of epithelial tumor cells. Understanding the interaction between NCS and the ligand is important for carrying out the targeted tumor therapy. In this study, we have investigated the biophysical interactions between NCS and 2-fluro Modified EpCAM RNA aptamer using Circular Dichroism (CD) and Infra-Red (IR) spectroscopy. The aromatic amino acid residues spanning the β sheets of NCS are found to participate in intermolecular interactions with 2 F Modified EpCAM RNA aptamer. In-silico modeling and simulation studies corroborate with CD spectra data. Furthermore, it reinforces the involvement of C and D1 strand of NCS in intermolecular interactions with EpCAM RNA aptamer. This the first report on interactions involved in the stabilization of NCS-EpCAM aptamer complex and will aid in the development of therapeutic modalities towards targeted cancer therapy.
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5
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Heterogeneous elastic network model improves description of slow motions of proteins in solution. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2014.11.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Moody P, Burlina F, Martin SR, Morgan RE, Offer J, Smith ME, Molloy JE, Caddick S. Evaluating the use of Apo-neocarzinostatin as a cell penetrating protein. Protein Eng Des Sel 2013; 26:277-81. [PMID: 23322746 PMCID: PMC3601848 DOI: 10.1093/protein/gzs104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 11/24/2012] [Accepted: 11/27/2012] [Indexed: 11/12/2022] Open
Abstract
Protein-ligand complex neocarzinostatin (NCS) is a small, thermostable protein-ligand complex that is able to deliver its ligand cargo into live mammalian cells where it induces DNA damage. Apo-NCS is able to functionally display complementarity determining regions loops, and has been hypothesised to act as a cell-penetrating protein, which would make it an ideal scaffold for cell targeting, and subsequent intracellular delivery of small-molecule drugs. In order to evaluate apo-NCS as a cell penetrating protein, we have evaluated the efficiency of its internalisation into live HeLa cells using matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry and fluorescence microscopy. Following incubation of cells with apo-NCS, we observed no evidence of internalisation.
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Affiliation(s)
- Paul Moody
- Department of Chemistry, University College London, Gordon Street, London WC1H 0AJ, UK
- Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Fabienne Burlina
- UPMC Univ Paris 06, CNRS, ENS, UMR 7203, Laboratoire des Biomolécules, 4 place Jussieu, 75 005 Paris, France
| | - Stephen R. Martin
- Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Rachel E. Morgan
- Department of Chemistry, University College London, Gordon Street, London WC1H 0AJ, UK
| | - John Offer
- Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Mark E.B. Smith
- Department of Chemistry, University College London, Gordon Street, London WC1H 0AJ, UK
| | - Justin E. Molloy
- Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Stephen Caddick
- Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
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YU HUI, ZHAO XI, FENG XIANLI, CHEN XUECHENG, BOROWIAK-PALEN EWA, HUANG XURI. MOLECULAR SIMULATIONS OF NEOCARZINOSTATIN CHROMOPHORE RELEASE MECHANISM. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2012. [DOI: 10.1142/s0219633612500927] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Neocarzinostatin (NCS) is an antitumor chromophore carrier protein with many applications in clinical use such as drug delivery system; however, so far its chromophore-releasing mechanism remains unclear. In this contribution the process and pathway of the chromophore releasing from holoprotein are revealed by conventional molecular dynamics simulations and essential dynamics (ED) sampling method. The results are consistent with the model for ligand release proposed in [D. H. Chin et al., J Biol Chem281:16025, 2006]. The further analysis suggests that the conformational changes of loop 99–104 and motions of side-chain of residue Phe78 are important factors for chromophore release; the opening state of loop 99–104 is a precondition for the release of ligand.
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Affiliation(s)
- HUI YU
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, P. R. China
| | - XI ZHAO
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, P. R. China
| | - XIAN-LI FENG
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, P. R. China
| | - XUECHENG CHEN
- Institute of Chemical and Environment Engineering, West Pomeranian University of Technology, Szczecinul. Pulaskiego 10, 70-322 Szczecin, Poland
| | - EWA BOROWIAK-PALEN
- Institute of Chemical and Environment Engineering, West Pomeranian University of Technology, Szczecinul. Pulaskiego 10, 70-322 Szczecin, Poland
| | - XU-RI HUANG
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, P. R. China
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Chi HW, Huang CC, Chin DH. Thiols Screened by the Neocarzinostatin Protein for Preserving or Detoxifying its Bound Enediyne Antibiotic. Chemistry 2012; 18:6238-49. [DOI: 10.1002/chem.201102825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 01/12/2012] [Indexed: 12/28/2022]
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Li Y, Liu Z, Wang R. Test MM-PB/SA on true conformational ensembles of protein-ligand complexes. J Chem Inf Model 2011; 50:1682-92. [PMID: 20695488 DOI: 10.1021/ci100036a] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The molecular mechanics Poisson-Boltzmann surface area (MM-PB/SA) method has been popular for computing protein-ligand binding free energies in recent years. All previous evaluations of the MM-PB/SA method are based upon computer-generated conformational ensembles, which may be affected by the defective computational methods used for preparing these conformational ensembles. In an attempt to reach more convincing conclusions, we have evaluated the MM-PB/SA method on a set of 24 diverse protein-ligand complexes, each of which has a set of conformations derived from NMR spectroscopy. Our results indicate that both MM-PB/SA and molecular mechanics generalized Born surface area (MM-GB/SA) are able to produce a modest correlation between their results and the experimentally measured binding free energies on our test set. In particular, both MM-PB/SA and MM-GB/SA produced better results by using a representative structure (R = 0.72-0.79) rather than averaging over the conformational ensemble of each given complex (R = 0.61-0.74). A head-to-head comparison with four selected scoring functions (X-Score, PLP, ChemScore, and DrugScore) on the same test set reveals that MM-PB/SA and MM-GB/SA results are marginally better than those produced by scoring funcitons, supporting the value of the MM-PB/SA method. Nevertheless, scoring functions are still more cost-effective options, especially for high-throughput tasks.
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Affiliation(s)
- Yan Li
- State Key Laboratory of Bioorganic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Science, Shanghai 200032, People's Republic of China
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Chi HW, Chien YC, Liu CY, Tseng CJ, Lee YJ, Chan JL, Chu YR, Chin DH. Role of Steric Effects in Protein-Directed Enediyne Cycloaromatization of Neocarzinostatin. Chemistry 2010; 17:1493-506. [DOI: 10.1002/chem.201002330] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2010] [Indexed: 12/15/2022]
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Releasing of the chromophore from the drug delivery protein C-1027: A molecular dynamics simulations study. J Struct Biol 2010; 172:284-93. [DOI: 10.1016/j.jsb.2010.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2010] [Revised: 08/12/2010] [Accepted: 08/18/2010] [Indexed: 11/19/2022]
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12
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Hariharan P, Sudhahar CG, Chou SH, Chin DH. Lipid Bilayer-Assisted Release of an Enediyne Antibiotic from Neocarzinostatin Chromoprotein. Biochemistry 2010; 49:7722-32. [DOI: 10.1021/bi100735v] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Parameswaran Hariharan
- Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan, ROC
- Institute of Biochemistry, National Chung Hsing University, Taichung 40227, Taiwan, ROC
| | | | - Shan-Ho Chou
- Institute of Biochemistry, National Chung Hsing University, Taichung 40227, Taiwan, ROC
| | - Der-Hang Chin
- Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan, ROC
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Wang B, Merz Jr. KM. Importance of loop dynamics in the neocarzinostatin chromophore binding and release mechanisms. Phys Chem Chem Phys 2010; 12:3443-9. [DOI: 10.1039/b924951f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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14
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Liang ZX. Complexity and simplicity in the biosynthesis of enediyne natural products. Nat Prod Rep 2010; 27:499-528. [DOI: 10.1039/b908165h] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Shanmuganathan A, Kumar TKS, Huang CM, Yu C, Chin DH. A superior drug carrier--aponeocarzinostatin in partially unfolded state fully protects the labile antitumor enediyne. J Biomed Sci 2009; 16:48. [PMID: 19463188 PMCID: PMC2694159 DOI: 10.1186/1423-0127-16-48] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 05/23/2009] [Indexed: 11/30/2022] Open
Abstract
Background Neocarzinostatin is a potent antitumor drug consisting of an enediyne chromophore and a protein carrier. Methods We characterized an intermediate in the equilibrium unfolding pathway of aponeocarzinostatin, using a variety of biophysical techniques including 1-anilino-8-napthalene sulfonate binding studies, size-exclusion fast protein liquid chromatography, intrinsic tryptophan fluorescence, circular dichroism, and 1H-15N heteronuclear single quantum coherence spectroscopy. Results The partially unfolded protein is in molten globule-like state, in which ~60% and ~20% tertiary and secondary structure is disrupted respectively. Despite lacking a fully coordinated tertiary structure for assembling a functional binding cleft, the protein in molten globule-like state is still able to fully protect the labile chromophore. Titration of chromophore leads the partially denatured apoprotein to fold into its native state. Conclusion These findings bring insight into conserving mechanism of neocarzinostatin under harsh environment, where even the partially denatured apoprotein exhibits protective effect, confirming the superiority of the drug carrier.
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Abstract
Antitumor antibiotic chromoproteins such as neocarzinostatin involve a labile toxin that is tightly bound by a protective protein with very high affinity but must also be freed to exert its function. Contrary to the prevalent concept of ligand release, we established that toxin release from neocarzinostatin requires no major backbone conformational changes. We report, herein, that subtle changes in the side chains of specific amino acid residues are adequate to gate the release of chromophore. A recombinant wild type aponeocarzinostatin and its variants mutated around the opening of the chromophore binding cleft are employed to identify specific side chains likely to affect chromophore release. Preliminary, biophysical characterization of mutant apoproteins by circular dichroism and thermal denaturation indicate that the fundamental structural characteristics of wild type protein are conserved in these mutants. The chromophore reconstitution studies further show that all mutants are able to bind chromophore efficiently with similar complex structures. NMR studies on 15N-labeled mutants also suggest the intactness of binding pocket structure. Kinetic studies of chromophore release monitored by time course fluorescence and quantitative high pressure liquid chromatography analyses show that the ligand release rate is significantly enhanced only in Phe78 mutants. The extent of DNA cleavage in vitro corresponds well to the rate of chromophore release. The results provide the first clear-cut indication of how toxin release can be controlled by a specific side chain of a carrier protein.
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Nakamura S, Ichiki SI, Takashima H, Uchiyama S, Hasegawa J, Kobayashi Y, Sambongi Y, Ohkubo T. Structure of Cytochrome c552 from a Moderate Thermophilic Bacterium, Hydrogenophilus thermoluteolus: Comparative Study on the Thermostability of Cytochrome c. Biochemistry 2006; 45:6115-23. [PMID: 16681384 DOI: 10.1021/bi0520131] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have studied the structure-thermostability relationship using cytochromes c from mesophilic and thermophilic bacteria; Pseudomonas aeruginosa (PAc(551)) growing at 37 degrees C and Hydrogenobacter thermophilus (HTc(552)) at 72 degrees C and showed that only five residues primarily differentiate their stabilities. For a more comprehensive study, we found Hydrogenophilus thermoluteolus (Pseudomonas hydrogenothermophila) growing at 52 degrees C and showed the moderate stability of the cytochrome c from this bacterium (PHc(552)). To explore the stabilization mechanisms, the crystal structure of PHc(552) was determined by X-ray analysis. The solution structure of HTc(552) elucidated previously by NMR was refined using distributed computational implementation. Furthermore, the recently reported crystal structure of HTc(552) has become available [Travaglini-Allocatelli, C. et al. (2005) J. Biol. Chem. 280, 25729-25734]. When the structures of these three cytochromes c were combined, this revealed that the five residues, corresponding to those mentioned above, determine the difference of stabilities among them as well. These facts suggested the stabilization mechanisms as follows: (1) improved van der Waals interactions by packing optimization at the N-terminal helix, (2) attractive electrostatic interactions with the heme propionate group, and (3) favorable van der Waals interaction with the heme. This comparative study, by supplementing the structural information of PHc(552) with its complementary feature, demonstrates that just a small number of amino acid residues determine the overall molecular stability by means of additivity of the effects of their substitutions. It is interesting that, in naturally occurring proteins, these adaptation strategies are accommodated by these bacteria to survive in the wide range of thermal conditions.
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Affiliation(s)
- Shota Nakamura
- Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-0871, Japan
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Tomioka Y, Kisara S, Yoshizawa S, Ozawa M, Suzuki N, Yamaguchi H, Hishinuma T, Mizugaki M, Goto J. Preparation of Neocarzinostatin Apoprotein Mutants and the Randomized Library on the Chromophore-Binding Cavity. Biol Pharm Bull 2006; 29:1010-4. [PMID: 16651736 DOI: 10.1248/bpb.29.1010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
W39F, F52Y, S98G, S98A, and S98C mutants of the neocarzinostatin apoprotein (apo-NCS) were newly prepared and investigated their physicochemical properties. The circular dichroism (CD) spectra of F78W, F52Y, S98A, S98G, S98C were superimposable with that of wild type 1R49 protein although the minor spectral change seemed to be in the ellipticity of W39F. The results suggest that position 52, 78, and 98 involving natural chromophore binding do not play a major role in the inducing overall structural changes of the protein. Conversely, the position 39 would be affected slightly. Ethidium bromide (EtdBr) binding to mutants was also evaluated by the monitoring of total fluorescence intensity and fluorescence polarization (FP). The observed dissociation constant in the FP study was 4.4 microM for wild type, 2.2 microM for S98A, 1.3 microM for S98G, 9.7 microM for S98C, respectively. When S98G and F52Y, the calculated maximum change of the total fluorescence intensity was increased, suggesting that the EtdBr binding to S98G or F52Y were slightly improved compared with the wild type. Then, a total of 14 amino acids randomly substituted phage displayed library of apo-NCS was successfully prepared, because substitution of the amino acid structured the chromophore-binding cavity were not change the overall structural features. The phages which bound glycyrrhetic acid conjugated bovine serum albumin were enriched from this library using phage display technique as the pilot experiments. Although more precision investigation still needs, it should be possible to select variants that have new functions not found in nature.
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Affiliation(s)
- Yoshihisa Tomioka
- Division of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
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