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Ng CA, Oehme DP, Kato Y, Tanokura M, Brownlee RTC. Binding of an RNA pol II Ligand to the WW Domain of Pin1 Using Molecular Dynamics Docking Simulations. J Chem Theory Comput 2015; 5:2886-97. [PMID: 26631800 DOI: 10.1021/ct900190n] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A novel docking protocol using a long, all atom molecular dynamics (MD) simulation, in an explicit solvent medium, without using any distance constraints is presented. This MD docking protocol is able to dock ligands, based on the C-terminal domain (CTD) of RNA polymerase II, into the tryptophan-tryptophan (WW) domain of Pin1. In this docking process, a significant loop-bending event occurs in order to encircle the ligand into its solvent exposed binding site, which cannot be simulated using current protocols. The simulations were validated structurally and energetically against an X-ray structure to confirm correct sampling of conformational space. Based on these simulations, and justification of the starting structure as a valid intermediate structure, a potential molecular basis for binding was predicted as well as confirming the key residues involved in the formation of the final strong and stable Pin1 WW domain-ligand complex.
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Affiliation(s)
- Chai Ann Ng
- Department of Chemistry, La Trobe University, VIC 3086, Australia, and Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Daniel P Oehme
- Department of Chemistry, La Trobe University, VIC 3086, Australia, and Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yusuke Kato
- Department of Chemistry, La Trobe University, VIC 3086, Australia, and Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Masaru Tanokura
- Department of Chemistry, La Trobe University, VIC 3086, Australia, and Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Robert T C Brownlee
- Department of Chemistry, La Trobe University, VIC 3086, Australia, and Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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2
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Ankers EA, Evison BJ, Phillips DR, Brownlee RTC, Cutts SM. Design, synthesis, and DNA sequence selectivity of formaldehyde-mediated DNA-adducts of the novel N-(4-aminobutyl) acridine-4-carboxamide. Bioorg Med Chem Lett 2014; 24:5710-5715. [PMID: 25453806 DOI: 10.1016/j.bmcl.2014.10.062] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/13/2014] [Accepted: 10/17/2014] [Indexed: 11/30/2022]
Abstract
A novel derivative of the anti-tumor agent N-[2-(dimethylamino)ethyl]acridine-4-carboxamide (DACA) was prepared by reduction of 9-oxoacridan-4-carboxylic acid to acridine-4-carboxylic acid with subsequent conversion to N-(4-aminobutyl)acridine-4-carboxamide (C4-DACA). Molecular modeling studies suggested that a DACA analogue comprising a side chain length of four carbons was optimal to form formaldehyde-mediated drug-DNA adducts via the minor groove. An in vitro transcription assay revealed that formaldehyde-mediated C4-DACA-DNA adducts selectively formed at CpG and CpA dinucleotide sequences, which is strikingly similar to that of formaldehyde-activated anthracenediones such as pixantrone.
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Affiliation(s)
- Elizabeth A Ankers
- Department of Chemistry, La Trobe Institute for Molecular Sciences, La Trobe University, Bundoora 3086, Australia
| | - Benny J Evison
- Department of Biochemistry, La Trobe Institute for Molecular Sciences, La Trobe University, Bundoora 3086, Australia; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Don R Phillips
- Department of Biochemistry, La Trobe Institute for Molecular Sciences, La Trobe University, Bundoora 3086, Australia
| | - Robert T C Brownlee
- Department of Chemistry, La Trobe Institute for Molecular Sciences, La Trobe University, Bundoora 3086, Australia
| | - Suzanne M Cutts
- Department of Biochemistry, La Trobe Institute for Molecular Sciences, La Trobe University, Bundoora 3086, Australia.
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3
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Oehme DP, Brownlee RTC, Wilson DJD. Can cyclic HIV protease inhibitors bind in a non-preferred form? An ab initio, DFT and MM-PB(GB)SA study. J Mol Model 2013; 19:1125-42. [DOI: 10.1007/s00894-012-1660-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 10/21/2012] [Indexed: 10/27/2022]
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4
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Oehme DP, Brownlee RTC, Wilson DJD. Effect of atomic charge, solvation, entropy, and ligand protonation state on MM-PB(GB)SA binding energies of HIV protease. J Comput Chem 2012; 33:2566-80. [DOI: 10.1002/jcc.23095] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 06/27/2012] [Accepted: 07/25/2012] [Indexed: 11/05/2022]
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5
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Abstract
Resistance remains a major issue with regards to HIV-1 protease, despite the availability of numerous HIV-1 protease inhibitors and copious amounts of structural and binding data. In an effort to improve our understanding of how HIV-1 protease is able to "outsmart" new drugs, we have investigated the flexibility of HIV-1 protease and in particular how it adapts to different structural stresses. Our analysis has highlighted the effects of space group on the variability between structures of HIV-1 protease and suggests that consideration of multiple structures and appropriate consideration of different conformations of the Ile50 residue is necessary in any structural analysis. Calculation of the root-mean-square deviation on a per-residue basis has been used to identify 'natural variation', while mutational and ligand analyses have been carried out to identify the effect on structure as a result of specific stresses. It was observed that mutations readily cause changes to occur at sites both close to and distant from a mutation site, with changes more likely to occur at residues that are sites of other major mutations. It is also revealed that HIV-1 protease adaption is dependent on the type and the structure of any bound ligand. Identification of the specific changes that occur due to these stresses will aid in the understanding of resistance and also aid in the design of new drugs.
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Affiliation(s)
- Daniel P Oehme
- Department of Chemistry and La Trobe Institute for Molecular Sciences (LIMS), La Trobe University , Bundoora, Victoria, 3086, Australia
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6
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Ng CA, Kato Y, Tanokura M, Brownlee RTC. Structural characterisation of PinA WW domain and a comparison with other group IV WW domains, Pin1 and Ess1. Biochim Biophys Acta 2008; 1784:1208-14. [PMID: 18503784 DOI: 10.1016/j.bbapap.2008.04.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 04/17/2008] [Accepted: 04/23/2008] [Indexed: 10/22/2022]
Abstract
The NMR solution structure of the PinA WW domain from Aspergillus nidulans is presented. The backbone of the PinA WW domain is composed of a triple-stranded anti-parallel beta-sheet and an alpha-helix similar to Ess1 and Pin1 without the alpha-helix linker. Large RMS deviations in Loop I were observed both from the NMR structures and molecular dynamics simulation suggest that the Loop I of PinA WW domain is flexible and solvent accessible, thus enabling it to bind the pS/pT-P motif. The WW domain in this structure are stabilised by a hydrophobic core. It is shown that the linker flexibility of PinA is restricted because of an alpha-helical structure in the linker region. The combination of NMR structural data and detailed Molecular Dynamics simulations enables a comprehensive structural and dynamic understanding of this protein.
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Affiliation(s)
- Chai Ann Ng
- Department of Chemistry, La Trobe University, VIC 3086, Australia
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7
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Aurelio L, Brownlee RTC, Hughes AB. Solution-Phase Peptide Synthesis; Synthesis of 'North-Western' and 'South-Eastern' Fragments of the Antifungal Cyclodepsipeptide Petriellin A. Aust J Chem 2008. [DOI: 10.1071/ch08132] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The solution-phase synthesis of two highly modified peptides, a hexamer and a heptamer, that constitute the two halves of the antifungal cyclic depsipeptide, Petriellin A, is reported.
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8
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Kato Y, Ng CA, Brownlee RTC, Tanokura M. PinA from Aspergillus nidulans binds to pS/pT-P motifs using the same Loop I and XP groove as mammalian Pin1. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 2007; 1774:1208-12. [PMID: 17693144 DOI: 10.1016/j.bbapap.2007.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 06/19/2007] [Accepted: 06/19/2007] [Indexed: 11/19/2022]
Abstract
Binding of the Cdc25c-T48 ligand to PinA from Aspergillus nidulans has been characterised by the identification of 15N and 1H resonances from 1H-15N HSQC NMR titration experiments using previous backbone assignments. It is shown that the binding site for the Cdc25c-T48 ligand with PinA is the same as in the mammalian protein Pin1, although with a reduced binding affinity. It had previously been proposed that the arginine residue (R17) in the loop I region of the Pin1 WW domain is essential for binding to the pSer/pThr-Pro motifs of phosphorylated ligands such as Cdc25c. In PinA, a fungal homologue of Pin1, the arginine residue (R17) is replaced with an asparagine residue (N17). The effect of substitution of R17 by N17 in Pin1 has been investigated via a computational study, which predicted that changing R17 to N17 in Pin1 lowers the ligand binding affinity as a result of reduced hydrogen bonding between the protein and the phosphate group of the ligand.
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Affiliation(s)
- Yusuke Kato
- Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraqi 305-8566, Japan
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9
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Cendron AC, Wines BD, Brownlee RTC, Ramsland PA, Pietersz GA, Hogarth PM. An FcgammaRIIa-binding peptide that mimics the interaction between FcgammaRIIa and IgG. Mol Immunol 2007; 45:307-19. [PMID: 17673295 DOI: 10.1016/j.molimm.2007.06.152] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 06/13/2007] [Accepted: 06/17/2007] [Indexed: 10/23/2022]
Abstract
A disulphide-constrained peptide that binds to the low affinity Fc receptor, FcgammaRIIa (CD32) has been identified and its structure solved by NMR. Linear (7-mer and 12-mer) and disulphide-constrained (7-mer) phage display peptide libraries were panned on recombinant soluble FcgammaRIIa genetically fused to HSA (HSA-FcgammaRIIa). Peptides were isolated only from the constrained peptide library and these contained the consensus sequence, CWPGWxxC. Phage clones displaying variants of the peptide consensus sequence bound to FcgammaRIIa and the strongest binding clone C7C1 (CWPGWDLNC) competed with IgG for binding to FcgammaRIIa and was inhibited from binding to FcgammaRIIa by the FcgammaRIIa-blocking antibody, IV.3, suggesting that C7C1 and IgG share related binding sites on FcgammaRIIa. A synthetic disulphide-constrained peptide, pep-C7C1 bound to FcgammaRIIa by biosensor analysis, albeit with low affinity (KD approximately 100microM). It was significant that the FcgammaRIIa consensus peptide sequence contained a Proline (Pro3), which when substituted with alanine abrogated FcgammaRIIa binding, consistent with Pro3 contributing to receptor binding. Upon binding of IgG and IgE to their respective Fc receptors (FcgammaRs and FcepsilonRI) Pro329 in the Fc makes a critical interaction with two highly conserved Trp residues (Trp90 and Trp113) of the FcRs. The NMR structure of pep-C7C1 revealed a stabilizing type II beta-turn between Trp2 and Trp5, with Pro3 solvent exposed. Modelling of the pep-C7C1 structure in complex with FcgammaRIIa suggests that Pro3 of C7C1 binds to FcgammaRIIa by inserting between Trp90 and Trp113 of FcgammaRIIa thereby mimicking the molecular interaction made between FcgammaRIIa and IgG.
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Affiliation(s)
- Angela C Cendron
- Burnet Institute, Austin Campus, Studley Road, Heidelberg, Vic. 3084, Australia
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10
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Schmid F, Separovic F, McDougall BM, Stone BA, Brownlee RTC, Seviour RJ. Characterisation of the extracellular polysaccharides produced by isolates of the fungus Acremonium. Carbohydr Res 2007; 342:2481-3. [PMID: 17669385 DOI: 10.1016/j.carres.2007.06.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Revised: 06/04/2007] [Accepted: 06/18/2007] [Indexed: 11/18/2022]
Abstract
Solid state (13)C NMR studies of the extracellular glucans from the fungi Acremonium persicinum C38 (QM107a) and Acremonium sp. strain C106 indicated a backbone of (1-->3)-beta-linked glucosyl residues with single (1-->6)-beta-linked glucosyl side branches for both glucans. Analyses of enzymatic digestion products suggested that the average branching frequency for the A. persicinum glucan (66.7% branched) was much higher than that of the Acremonium sp. strain C106 glucan (28.6% branched). The solid state (13)C NMR spectra also indicated that both glucans are amorphous polymers with no crystalline regions, and the individual chains are probably arranged as triple helices.
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Affiliation(s)
- Frank Schmid
- Biotechnology Research Centre, La Trobe University, Bendigo, VIC 3550, Australia
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11
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Ng CA, Zhao W, Dang J, Bergdahl M, Separovic F, Brownlee RTC, Metzger RP. The conformation of acetylated virginiamycin M1 and virginiamycin M1 in explicit solvents. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 2007; 1774:610-8. [PMID: 17442646 DOI: 10.1016/j.bbapap.2007.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Revised: 02/14/2007] [Accepted: 03/06/2007] [Indexed: 11/19/2022]
Abstract
The three-dimensional structure of acetylated virginiamycin M(1) (acetylated VM1) in chloroform and in a water/acetonitrile mixture (83:17 v/v) have been established through 2D high resolution NMR experiments and molecular dynamics modeling and the results compared with the conformation of the antibiotic VM1 in the same and other solvents. The results indicated that acetylation of the C-14 OH group of VM1 caused it to rotate about 90 degrees from the position it assumed in non-acetylated VM1. The conformation of both VM1 and acetylated VM1 appear to flatten in moving from a nonpolar to polar solvent. However, the acetylated form has a more hydrophobic nature. The acetylated VM1 in chloroform and in water/acetonitrile solution had a similar configuration to that of VM1 bound to 50S ribosomes and to the Vat(D) active sites as previously determined by X-ray crystallography. Docking studies of VM1 to the 50S ribosomal binding site and the Vat(D) gave conformations very similar to those derived from X-ray crystallographic studies. The docking studies with acetylated VM1 suggested the possibility of a hydrogen bond from the acetyl carbonyl group oxygen of acetylated VM1 to the 2' hydroxyl group of ribose of adenosine 2538 at the ribosomal VM1 binding site. No hydrogen bonds between acetylated VM1 and the Vat(D) active sites were found; the loss of this binding interaction partly accounts for the release of the product from the active site.
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Affiliation(s)
- Chai Ann Ng
- Department of Chemistry, La Trobe University, VIC 3086, Australia
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12
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Dinev Z, Wardak AZ, Brownlee RTC, Williams SJ. A convenient gram-scale synthesis of uridine diphospho(13C6)glucose. Carbohydr Res 2006; 341:1743-7. [PMID: 16603138 DOI: 10.1016/j.carres.2006.02.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 02/20/2006] [Accepted: 02/24/2006] [Indexed: 10/24/2022]
Abstract
A simple gram-scale synthesis of uridine diphospho(13C6)glucose is presented from D-(13C6)glucose. The critical step uses a 1H-tetrazole-catalyzed coupling of 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl-1-phosphate and UMP-morpholidate. The uridine diphospho(13C6)glucose was used in the structural identification of (1-->3)-beta-D-glucan from Lolium multiflorum.
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Affiliation(s)
- Zoran Dinev
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
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13
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Schmid F, Stone BA, Brownlee RTC, McDougall BM, Seviour RJ. Structure and assembly of epiglucan, the extracellular (1→3;1→6)-β-glucan produced by the fungus Epicoccum nigrum strain F19. Carbohydr Res 2006; 341:365-73. [PMID: 16359651 DOI: 10.1016/j.carres.2005.10.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2005] [Accepted: 10/30/2005] [Indexed: 11/16/2022]
Abstract
In a previous article [Carbohydr. Res.2001, 331, 163-171] two different structures for the possible modular repeating unit of the extracellular beta-glucan, epiglucan produced by the fungus Epicoccum nigrum strain F19 were proposed. Clarifying which was the more likely one was considered essential before attempts were made to understand how epiglucan was assembled by this fungus. Data from Smith degradation analyses of epiglucan were consistent with the repeating unit of structure I, where single glucosyl residues are attached by (1-->6)-beta-linkages to two out of every three glucosyl residues in the (1-->3)-beta-linked glucan backbone. Repeated Smith degradations of 14C-glucose labelled epiglucan showed that chain elongation occurred from its non-reducing end. Side chain insertion into the growing glucan was followed by analysis of real time incorporation of 13C-glucose into epiglucan by 13C NMR, and 14C-glucose by enzymic digestion of the synthesised 14C-epiglucan. All data obtained were consistent with the view that single (1-->6)-beta-linked glucosyl side residues are inserted simultaneously as the glucan backbone elongates.
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Affiliation(s)
- Frank Schmid
- School of Agriculture and Wine, The University of Adelaide, PMB1, Glen Osmond, SA 5064, Australia
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14
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Abstract
Petriellin A is a novel cyclic depsipeptide antifungal compound consisting of nine l-configured residues, one d-phenyllactic acid (PhLac) and three unknown chiral centres: two N-methyl-threonines (MeThr1 & MeThr2) and one N-methyl-isoleucine (MeIle). NMR experiments including 2D ROESY, NOESY along with structural and energy calculations predicted that the unknown chiral centres were all l-configured, which was later verified chemically. Simulated annealing, dynamics calculations and minimisation processes showed Petriellin A to have a folded "C-shaped" structure.
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Affiliation(s)
- Jason Dang
- Department of Chemistry, La Trobe University, VIC 3086, Australia.
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15
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Abstract
We report the full structural determination of the depsipeptide petriellin A. The absolute configuration of the amino acid residues, N-methyl isoleucine and N-methyl threonine, have been determined by a combination of HPLC and TLC comparison of synthetic Marfey’s derivatives and Marfey’s derivatives of the natural product hydrolysate. The configuration of the chiral centres in these two N-methylated residues was found to be the same as those of the common unmethylated l-amino acids.
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Affiliation(s)
- Luigi Aurelio
- Department of Chemistry, La Trobe University, Victoria 3086, Australia
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17
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Dang J, Metzger RP, Brownlee RTC, Ng CA, Bergdahl M, Separovic F. The conformational flexibility of the antibiotic virginiamycin M(1). Eur Biophys J 2005; 34:383-8. [PMID: 15834559 DOI: 10.1007/s00249-005-0464-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2004] [Revised: 12/23/2004] [Accepted: 01/05/2005] [Indexed: 10/25/2022]
Abstract
The antibiotic virginiamycin is a combination of two molecules, virginiamycin M(1) (VM1) and virginiamycin S(1) (VS1) or analogues, which function synergistically by binding to bacterial ribosomes and inhibiting bacterial protein synthesis. Both VM1 and VS1 dissolve poorly in water and are soluble in more hydrophobic solvents. We have recently reported that the 3D conformation of VM1 in CDCl(3) solution differs markedly from the conformation bound to a VM1 binding enzyme and to 50S ribosomes as found by X-ray crystallographic studies. We now report the results of further NMR studies and subsequent molecular modeling of VM1 dissolved in CD(3)CN/H(2)O and compare the structure with that in CD(3)OD and CDCl(3). The conformations of VM1 in CD(3)CN/H(2)O, CD(3)OD and CDCl(3) differ substantially from one another and from the bound form, with the aqueous form most like the bound structure. We propose that the flexibility of the VM1 molecule in response to environmental conditions contributes to its effectiveness as an antibiotic.
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Affiliation(s)
- Jason Dang
- Department of Chemistry, La Trobe University, Melbourne, VIC 3086, Australia
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18
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Dang J, Bergdahl M, Separovic F, Brownlee RTC, Metzger RP. Solvent affects the conformation of virginiamycin M1 (pristinamycin IIA, streptogramin A). Org Biomol Chem 2004; 2:2919-24. [PMID: 15480455 DOI: 10.1039/b407724e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The streptogramins are antibiotics which act by binding two different components at separate nearby sites on the bacterial 50S ribosome, inhibiting protein synthesis. The first component, a macrolactone, is common to many of the streptogramin antibiotics and, thus, is referred to by many names including virginiamycin M1(VM1), pristinamycin IIA, ostreogrycin A and streptogramin A. X-Ray crystallographic studies of VM1 bound to ribosomes and to a deactivating enzyme show a different conformation to that of VM1 in chloroform solution. We now report the results of high resolution 2D NMR experiments that show that the conformation of VM1 in dimethyl sulfoxide and methanol differs from both that in chloroform solution and in the bound form. The 3D structure and the 1H NMR and 13C NMR chemical shifts of VM1 in dimethyl sulfoxide and methanol are described.
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Affiliation(s)
- Jason Dang
- School of Chemistry, LaTrobe University, VIC, Australia
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19
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Dang J, Bergdahl BM, Separovic F, T. C. Brownlee R, P. Metzger R. Difference in Conformation of Virginiamycin M1 in Chloroform and Bound Form in the 50S Ribosome or Streptogramin Acetyltransferase. Aust J Chem 2004. [DOI: 10.1071/ch03326] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The conformation of virginiamycin M1 (VM1) in chloroform, determined by high-resolution NMR experiments, differs significantly from that of the X-ray crystal structure of VM1 bound to the 50S ribosome and to the active site of a streptogramin acetyltransferase enzyme. This implies that the binding process to these entities causes a major change in VM1 conformation.
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20
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Aurelio L, Box JS, Brownlee RTC, Hughes AB, Sleebs MM. An efficient synthesis of N-methyl amino acids by way of intermediate 5-oxazolidinones. J Org Chem 2003; 68:2652-67. [PMID: 12662035 DOI: 10.1021/jo026722l] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-Methyl amino acids occur in many natural products. Experimental strategies are presented for a unified approach to the synthesis of N-methyl derivatives through 5-oxazolidinones of the 20 common l-amino acids. The amino acids with reactive side chains that required protecting groups or devoted syntheses for side chain construction for N-methylation to proceed included serine, threonine, tyrosine, cysteine, methionine, tryptophan, asparagine, histidine, and arginine. The studies have provided improved methods for the preparation of N-methyl serine, threonine, and tyrosine. All 20 of the common l-amino acids are now available in suitable forms for solid or solution-phase peptide synthesis.
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Affiliation(s)
- Luigi Aurelio
- Department of Chemistry, La Trobe University, Melbourne, Victoria 3086, Australia
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21
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Abstract
[reaction: see text] N-Methyl amino acid residues in peptides modify several pharmacologically useful parameters, but synthesis of alkylated peptides is hampered by unavailability of N-methylated monomers. The syntheses of four N-methyl amino acids with basic side chains are presented. The side chains of these basic amino acids needed to be specially protected or constructed. This completes the set of 20 common L-amino acid N-methyl derivatives prepared via 5-oxazolidinone intermediates by our group.
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Affiliation(s)
- Luigi Aurelio
- Department of Chemistry, La Trobe University, Victoria 3086, Australia
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Craik DJ, Levy GC, Brownlee RTC. Substituent effects on nitrogen-15 and oxygen-17 chemical shifts in nitrobenzenes: correlations with electron densities. J Org Chem 2002. [DOI: 10.1021/jo00158a006] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Masters AF, Brownlee RTC, O'Connor MJ, Wedd AG. Applications of molybdenum-95 nuclear magnetic resonance spectroscopy. 3. Arenemolybdenum tricarbonyl derivatives. Inorg Chem 2002. [DOI: 10.1021/ic50226a031] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bromilow J, Brownlee RTC, Lopez VO, Taft RW. Para-substituent C-13 chemical shifts in substituted benzenes. 1. Updating the .sigma.R0 scale and analysis of aprotic solvent effects. J Org Chem 2002. [DOI: 10.1021/jo00394a005] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bromilow J, Brownlee RTC. Investigating the .sigma.+ resonance scale using carbon-13 nuclear magnetic resonance shifts. Graphical representation of the dual substituent parameter equation. J Org Chem 2002. [DOI: 10.1021/jo01322a016] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Scrofani SDB, Brownlee RTC, Sadek M, Wedd AG. Sequence-specific 1H, 13C, and 15N NMR assignments for oxidized ferredoxin from Clostridium pasteurianum. Inorg Chem 2002. [DOI: 10.1021/ic00119a016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bromilow J, Brownlee RTC, Craik DJ, Sadek M, Taft RW. Nonadditive carbon-13 nuclear magnetic resonance substituent shifts in 1,4-disubstituted benzenes. Nonlinear resonance and shift-charge ratio effects. J Org Chem 2002. [DOI: 10.1021/jo01300a033] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Craik DJ, Brownlee RTC, Sadek M. Transmission of substituent effects via molecular lines of force: defense of the DSP method and an illustration of its use in explaining .pi. polarization. J Org Chem 2002. [DOI: 10.1021/jo00343a011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Brownlee RTC, Shehan BP, Wedd AG. Applications of molybdenum-95 NMR spectroscopy. 17. Molybdenum-95 and nitrogen-14 relaxation time measurements confirming that octacyanomolybdate(4-) is dodecahedral in aqueous solution. Inorg Chem 2002. [DOI: 10.1021/ic00260a003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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Gheller SF, Hambley TW, Rodgers JR, Brownlee RTC, O'Connor MJ, Snow MR, Wedd AG. Synthesis and characterization of complexes of thiomolybdates and thiotungstates with copper(I) and silver(I) cyanides, including molybdenum-95 and tungsten-183 NMR properties and the crystal and molecular structures of (n-Pr4N)2[(CN)CuS2MoS2], (n-Pr4N)2[(CN)AgS2WS2], and (Ph4As)2[(CN)CuS2MoS2Cu(CN)].H2O. Inorg Chem 2002. [DOI: 10.1021/ic00184a029] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Masters AF, Bosbard GE, George TA, Brownlee RTC, O'Connor MJ, Wedd AG. Applications of molybdenum-95 NMR. 8. Molybdenum(0) carbonyl derivatives of phosphines, phosphites and related ligands. Inorg Chem 2002. [DOI: 10.1021/ic00148a014] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gheller SF, Hambley TW, Brownlee RTC, O'Connor MJ, Snow MR, Wedd AG. Applications of molybdenum-95 NMR spectroscopy. 7. Studies of metal-metal bonded systems including aqueous molybdenum(IV) and molybdenum(V). Crystal and molecular structure of Na2[Mo3O4((O2CCH2)2NCH3)3].7H2O. J Am Chem Soc 2002. [DOI: 10.1021/ja00344a020] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Boskovic C, Sadek M, Brownlee RTC, Bond AM, Wedd AG. Electrosynthesis and solution structure of six-electron reduced forms of metatungstate, [H2W12O40]6− †. ACTA ACUST UNITED AC 2001. [DOI: 10.1039/b006264m] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
A range of oxazolidinones derived from N-carbamoyl
α-amino acids were prepared by an efficient method as key intermediates
in the synthesis of N-methyl amino acids and peptides.
The method was readily applied to most α-amino acids except those with
basic side chains. The oxazolidinones were converted by reductive cleavage
into N-methyl α-amino acids.
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Boskovic C, Wedd AG, Sadek M, Brownlee RTC, Bond AM. Lifting the lid on metatungstate. 1H and 183W NMR study of the six electron reduced anion [(H)2{WIV3(OH2)3}WVI9O34(OH)3]3−. Chem Commun (Camb) 1999. [DOI: 10.1039/a900088g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Way DM, Cooper JB, Sadek M, Vu T, Mahon PJ, Bond AM, Brownlee RTC, Wedd AG. Systematic Electrochemical Synthesis of Reduced Forms of the alpha-[S(2)Mo(18)O(62)](4)(-) Anion. Inorg Chem 1998; 37:604. [PMID: 11670315 DOI: 10.1021/ic9714192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Way DM, Cooper JB, Sadek M, Vu T, Mahon PJ, Bond AM, Brownlee RTC, Wedd AG. Systematic Electrochemical Synthesis of Reduced Forms of the α-[S2Mo18O62]4-Anion1. Inorg Chem 1997. [DOI: 10.1021/ic970592v] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- David M. Way
- Department of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia, Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia
| | - John B. Cooper
- Department of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia, Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Maruse Sadek
- Department of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia, Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Truc Vu
- Department of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia, Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Peter J. Mahon
- Department of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia, Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Alan M. Bond
- Department of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia, Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Robert T. C. Brownlee
- Department of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia, Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Anthony G. Wedd
- Department of Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia, Department of Chemistry, Monash University, Clayton, Victoria 3168, Australia, and School of Chemistry, University of Melbourne, Parkville, Victoria 3052, Australia
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Young CG, Kocaba TO, Sadek M, Brownlee RTC, Tiekink ERT. Tris(N,N-dialkyldithiocarbamato-S,S')thiotungsten(VI) Complexes and the X-Ray Crystal Structure of [WS(S2CNEt2)3]BF4. Aust J Chem 1994. [DOI: 10.1071/ch9942075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The orange, diamagnetic compounds [WS(S2CNR2)3]X(R = Me, X- = BF4-,
BPh4-;R = Et, X- =BF4-) were prepared by reacting WSCl4 and Me3SiS2CNR2 in dichloromethane, followed by metathesis with NaX in methanol. The compounds were characterized by elemental analysis, infrared and variable-temperature 1H n.m.r. spectroscopy and X-ray crystallography. Crystals of [WS(S2CNEt2)3] BF4 were monoclinic, space group P21/a with a 12.293(1), b 17.229(5), c 14.257(2) Ǻ,β 113.69(1)°, V 2765(2) Ǻ3 and Dc = 1.796 g cm-3 for Z = 4. The structure was solved by the Patterson method and refined by a full-matrix least-squares procedure, 3961data being used, to a conventional R value of 0.039 ( Rw = 0.040). The seven-coordinate cation possesses a pentagonal-bipyramidal geometry; the terminal thio ligand [W=S 2.127(2)Ǻ] occupies an axial position, a unique dithiocarbamate ligand spans the other axial position and an equatorial position while the two other dithiocarbamate ligands occupy the four remaining equatorial sites.
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Chiu FCK, Brownlee RTC, Phillips DR. Cupric Ion Chelation Assisted Synthesis of N(α)-Protected N(ω)-Acridin-9-yl α,ω-Diamino Carboxylic Acids. Aust J Chem 1993. [DOI: 10.1071/ch9931207] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The synthesis of Nα-protected Nω-acridin-9-yl derivatives of the α,w-diamino carboxylic acids ornithine and lysine is reported. Direct introduction of the acridin-9-yl moiety to the amino side chain of the free amino acid was achieved in methanol through temporary copper(II) chelation protection of the α-amino and
carboxy groups. Nα-Fmoc protection was introduced by using N-(fluoren-9-ylmethoxycarbonyloxy)succinimide in aqueous dioxan.
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Brownlee RTC, Shehan BP, Wedd AG. Applications of 95Mo N.M.R. Spectroscopy. XVIII. Relaxation Times, Quadrupole Coupling Constants and Partial Field Gradients in [Mo(CO)5L] Complexes. Aust J Chem 1988. [DOI: 10.1071/ch9881457] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A study of ,95Mo spin-lattice relaxation times (T1) and linewidths of [Mo(CO)5L] complexes, where L = PPh3, AsPh3, SbPh3, pyridine and Cl-, has shown that the relaxation times are due entirely to the quadrupolar mechanism, with no scalar coupling contribution to linewidth where molybdenum is bonded to a quadrupolar nucleus. Based on the literature value of the quadrupole coupling constant obtained by n.q.r . for the PPh3 complex (1.972 MHz), the quadrupole coupling constants of the arsine and stibine complexes are determined to be 3.36 and 3.75 MHz respectively. These values, and that of the pyridine complex (2.80 MHz), are found to correlate with ligand partial field gradient parameters obtained from Mossbauer spectra of FeII complexes, and are rationalized in terms of metal- ligand bonding interactions. For Et4N [Mo(CO)5Cl], the correlation is very poor; this result is attributed to the effects of ion in solution.
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Brownlee RTC, Oconnor MJ, Shehan BP, Wedd AG. Applications of 95Mo N.M.R-Spectroscopy. XVI. Structure and Bonding in [Mo(Co)3(η6-Arene)] Complexes From 95Mo,13C and 17O Relaxation-Times. Aust J Chem 1986. [DOI: 10.1071/ch9860931] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Spin-lattice relaxation times (T1) have been measured for the 95Mo, 17O and methine and carbonyl 13C nuclei for a series of [Mo(CO)3(η6-C6H6- nMen)] complexes. In addition to the expected decrease in T1 with increasing molecular volume, the 95Mo and methine 13C data are interpreted in terms of variations in arene -molybdenum bonding. The methine 13C T1 values decrease in the order o- xylene > toluene > p- xylene > m- xylene > mesitylene . The methyl substitution pattern determines the distribution of electron-rich sites on the arene ligand , affecting the molybdenum- arene bond strength and the barrier to arene rotation. These observations support an earlier proposal that downfield 95Mo chemical shifts are associated with increased molybdenum- arene bond strength. 95Mo T1 values are unaffected by the rotational barriers, since they depend only on molecular tumbling perpendicular to the pseudo C3v symmetry axis. While these T1 values decrease as the number of methyl groups increases, an effect due to increasing molecular volume, the order of 95Mo T1 for the xylene complexes is opposite to that of the 13C T1, due to a reduction in the electric field gradient at the 95Mo nucleus. 95Mo quadrupole coupling constants for the series are 1.2�0.2 MHz. The 17O T1 values have also been measured for this series. They are considerably longer, and quadrupole coupling constants smaller (0.87�0.07 MHz), than those of other metallocarbonyls , indicating a significant increase in metal- ligand dπ-pπ - back bonding in the present system. A correlation between carbonyl force constants and 17O quadrupole coupling constants is presented.
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Brownlee RTC, Cacioli P, Chandler CJ, Phillips DR, Scourides PA, Reiss JA. The synthesis and characterization of a series of bis-intercalating bis-anthracyclines. ACTA ACUST UNITED AC 1986. [DOI: 10.1039/c39860000659] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
The configurations of the (E)- and (Z)-β- methylcinnamic acids and their methyl esters have been confirmed by 1H and 13C n.m.r . spectroscopy.
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Gheller SF, Sidney M, Masters AF, Brownlee RTC, O'Conner MJ, Wedd AG. Applications of molybdenum-95 N.M.R. spectroscopy. X. Polyoxomolybdates. Aust J Chem 1984. [DOI: 10.1071/ch9841825] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An initial survey of the 95Mo
n.m.r. properties of a range of 12 polyoxomolybdates
is presented. The species resonate in the range - 18 to + 140 ppm. The observed line widths generally exceed 100 Hz for
six-coordinate molybdenum sites of low symmetry, but can be narrow (< 20 Hz
at 20�) for four-coordinate sites. Aqueous solutions of [Mo7O24]6-
at pH 6.1 exhibit exchange between Mo- and Mo7-based species.
Solutions of α-[Mo8O26]4- in MeCN feature a single narrow resonance (δ16, Wh/2 23 Hz at 20�) assigned to the
tetrahedral capping sites, while two broad resonances (δ19, Wh/2 240 Hz; δ109, Wh/2 C. 270 HZ) are seen in
equivalent solutions of β-[Mo8O26]4-. In
the cases cited above, 17O n.m.r. is used to confirm the integrity
of sample solutions and assists in correction of the 95Mo n.m.r.
properties of β-[Mo8O26]4 reported in a
previous communication.
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Brownlee RTC, Sadek M, Craik DJ. Ab initio MO calculations and17O NMR at natural abundance ofpara-substituted acetophenones. ACTA ACUST UNITED AC 1983. [DOI: 10.1002/omr.1270211005] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Andrews PR, Brownlee RTC, Mackay MF, Poulton DB, Sadek M, Winkler DA. Conformational analysis of picrotoxinin by N.M.R., X-ray crystallography, and molecular orbital and classical potential-energy calculations. Aust J Chem 1983. [DOI: 10.1071/ch9832219] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The conformation of the
potent convulsant drug picrotoxinin has been studied by proton n.m.r., X-ray
crystallography, molecular orbital calculations and classical calculations. The
calculations reveal two alternative low-energy conformations, either of which
is consistent with the n.m.r. data, and one of which is also observed
crystallographically. The energy difference is sufficiently small to suggest
that either conformation may be the biologically active form.
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Gheller SF, Hambley TW, Traill PR, Brownlee RTC, O'Conner MJ, Snow MR, Wedd AG. Applications of molybdenum-95 N.M.R. spectroscopy. VI. 95Mo and 13C N.M.R. of certain cis-dioxomolybdenum(VI) compounds and related species. The crystal and molecular structure of Bis(N,N-diethylhydroxylamido(l -)-O,N)- disulfidomolybdenum(VI) hemibenzene. Aust J Chem 1982. [DOI: 10.1071/ch9822183] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The 95MO n.m.r.
spectra of a series of compounds containing the fac-[MoVIO3] and cis-[ MoVIO2] units are reported, together
with those for the series [MoX2(R2NO)2] (X = O
or S; R = Et, PhCH2). Trends in the data are discussed. The
stereochemistry in solution of certain of the cis-dioxo species is assigned by means of 13C n.m.r.
spectroscopy. The crystal and molecular structure of [MoS2(Et2NO)2],0.5C6H6
has been determined by X-ray crystallography. The steric and electronic
requirements of the terminal sulfide ligands significantly affect the detailed
coordination geometry relative to that observed for the dioxo analogue [MoO2(Et2NO)2].
Crystal data: a 10.162(2), b 11.836(2), c 14.437(2) �, β 106.12(2)� P21/a; Z 4.
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Brownlee RTC, Craik DJ. The relationship between19F and13C substituent chemical shifts and electron densities. 2—p-phenylacetyl fluorides. ACTA ACUST UNITED AC 1981. [DOI: 10.1002/mrc.1270150308] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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