ISSN:0749-1581    

DOI:10.1002/mrc.1260311302

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0749-1581    

DOI:10.1002/mrc.1260311303

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractA 3D NOE‐NOE spectrum of the paramagnetic protein met‐cyanomyoglobin has been successfully obtained. The protein shows hyperfine shifted signals. Planes at their frequencies show clean cross peaks with signals of nearby protons. Connectivities can be detected in‐plane at frequencies corresponding to hyperfine broadened signals beneath the diamagnetic envelope, whose connectivities may be difficult to observe otherwise. The limits of observability of cross peaks are discussed by means of spectral simula

ISSN:0749-1581    

DOI:10.1002/mrc.1260311304

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

Abstract1H NMR saturation transfer experiments were successfully used in connecting iron(III) high‐ and low‐spin forms of equine, the molluscDolabella auriculariaand the sharkMustelus japonicusmyoglobins. With the known signal assignments in the high‐spin form, a haem peripheral proton resonances in met‐azido and met‐imidazole complexes of the myoglobins have been straightforwardly assigned via the saturation transfer connectivities. Analysis of the extent of the saturation transfer provided the kinetics of the ligand

ISSN:0749-1581    

DOI:10.1002/mrc.1260311305

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThrough 1D and 2D NOESY experiments, samples of copper‐cobalt superoxide dismutase in which the histidines had been completely deuteriated except for the β‐CH2protons were investigated. In this way a simplified spectrum was obtained which allowed the detection of the His NHs of the cobalt domain and their assignment through the kinetics of the proton‐deuterium exchange. Further, the β‐CH2protons of Asp 83 were stereospecifically assigned throughT1measurements. Some backbone protons were also

ISSN:0749-1581    

DOI:10.1002/mrc.1260311306

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe binding of trimethylphosphine to the axial position of the haeme iron in modified cytochromecby alkylation of methionine was studied by NMR spectroscopy. Electron self‐exchange was determined by spin‐lattice relaxation time (T1) measurement. The rate is 7.5 × 1031 mol−1s−1at 25°C in 0.1 M phosphate buffer (pH 7.0). Two‐dimensional transfer spectroscopy was used to locate haeme methyl resonances in both iron(II) and iron(III) complexes of modified

ISSN:0749-1581    

DOI:10.1002/mrc.1260311307

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractA1H 2D NMR investigation of the oxidized 2[4Fe‐4S] ferredoxins fromClostridium pasteurianumandC. aciduriciwas carried out. Sequential assignments through standard HOHAHA and NOESY procedures were obtained for the 2–7, 23–36 and 52–55 sequence segments of both proteins. Additional assignments of the 15–17 and 44–46 segments, linking the clusters, and of a few other residues were made by taking advantage of sequence differences between the two proteins. In summary, only the immediate vicinity of the cysteine ligands could not be identified by the procedure. In these small 2[4Fe‐4S] ferredoxins, a large proportion of the resonances is sensitive to the presence of the paramagnetic centres and does not easily display NOE correlations. Nevertheless, long‐range NOE peaks that could be observed shed light on the solution structure of these proteins. The close interaction between the N‐ and C‐termini, previously evidenced by x‐ray crystallography, was confirmed for both proteins in solution. Small differences between the ferredoxins fromC. pasteurianumandC. aciduriciwere detected in the flexible and variable external 25–30 loop and also in the region separating the clusters. These differences may correlate with small dissimilarities previously observed between some properti

ISSN:0749-1581    

DOI:10.1002/mrc.1260311308

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractAn Fe(II) complex with Z‐Ala‐CysProLeuCysGlyNHC6H4mF (Z = benzoxylcarbonyl) having an invariant bidentate peptide ligand, CysKYCys, in rubredoxins was synthesized. The contact‐shifted1H,2H and19F NMR signals of (Et4N)2[Fe(ZAlacysProLeucysGlyNHC6H4mF)2] (1) in acetonitrile‐d3or acetonitrile at 30°C indicate the existence of two isomers (δ and λ) in the solution of bidentate complex 1 with different orientations of the bidentate peptide ligand to a tetrahedral Fe(II) ion. A novel tetradentate cysteine‐containing peptide ligand,cis‐1,2‐cyclohexylene(COAlaCysProLeuCysGlyNHC6H4mF)2, is designed by energy minimum calculations and synthesized. Its Fe(II) complex, (Et4N)2[Fe(cis‐1,2‐cyclohexylene(CO‐Ala‐cys‐Pro‐Leu‐cys‐Gly‐NH‐C6H4‐m‐F)2)], showed only set

ISSN:0749-1581    

DOI:10.1002/mrc.1260311309

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

Abstract1H two‐dimensional NMR experiments on nickel(II)‐substituted azurin have been successfully applied. Despite the short relaxation times of the hyperfine‐shifted resonances, the combined use of NOESY and COSY spectra allowed the assignment of 15 resonances belonging to the metal‐coordinated residues Gly‐45, His‐46, His‐117 and Met‐121. Even in the case of the two broad and furthest downfield resonances, the NOESY spectra were successful in assigning these signals to the β‐CH2protons of Cys‐112. The protons of the non‐coordinated residues Met‐13, Phe‐15 and Trp‐48 were also assigned via NOESY

ISSN:0749-1581    

DOI:10.1002/mrc.1260311310

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractAddition of aryl Grignard reagents to an iron(III) tetraphenylporphyrin π cation radical, [(TPP⋅)FeIIICl] (SbCl6), in dichloromethane solution at 202 K yields a mixture of σ‐phenyl iron(IV) tetraphenylporphyrin, [(TPP)FeIV(Ph)] (SbCl6), and σ‐phenyl iron(III) tetraphenylporphyrin, (TPP)FeIIICl. A σ‐phenyliron(III) complex is also formed by nucleophilic addition to the tetraphenylporphyrin macrocycle accompanied by σ‐phenyl axial coordination. The complexes formed were identified by1H NMR spectroscopy. A new route for generating σ‐aryl iron(IV) porphyrin species from the iron(III) porphyrin π cation radical was established. The characteristic1H NMR pattern of the low‐spin iron(III) porphyrin ring modified species reflects itsCssymmetry and includes four upfield‐shifted pyrrole resonances (2.31, −10.40, 20.39 and −20.87 ppm, 202 K) accompanied by a set of σ‐phenyl resonances (ortho, −188.4;p‐H, −102.5;p‐CH3for σ‐p‐tolyl, 162.3 ppm). Analysis of the paramagnetic shifts of the σ‐phenyl (σ‐p‐tolyl) ligand of the new species indicates a high π spin density consistent with the electronic structure of low‐spin iron(III) and the contribution of a σ‐delocalization mechanism via donation from a filled σ‐phenyl orbital to an emptydz2; orbital. The formation of a low‐spin σ‐phenyliron(III) isoporphyrin or low‐spin σ‐phenylN‐arylporphyrin is considered. Themesosubstitution can be accounted for by a mechanism which emphasizes the radical nature of

ISSN:0749-1581    

DOI:10.1002/mrc.1260311311

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY