Magnetic circular dichroic spectra of cobalt(II) substituted metalloenzymes

Holmquist, Barton; Kaden, Thomas A.; Vallée, Bert L.

doi:10.1021/bi00678a016

Cited by 69 publications

(54 citation statements)

References 30 publications

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“…2). These features are also reflected in the CD and MCD spectra, the latter indicating, in addition, that the metal remains coordinated tetrahedrally (27). The interaction generates a distinct new transition, Xmax 338 nm, E _ 900 M-1 cm-1, which is apparent also in the CD spectrum as a negative shoulder at 338 nm and in the MCD spectrum ( (Fig.…”

Section: Resultsmentioning

confidence: 79%

Metal-coordinating substrate analogs as inhibitors of metalloenzymes.

Holmquist¹,

Vallée²

1979

Proc. Natl. Acad. Sci. U.S.A.

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Section: Resultsmentioning

confidence: 79%

Metal-coordinating substrate analogs as inhibitors of metalloenzymes.

Holmquist¹,

Vallée²

1979

Proc. Natl. Acad. Sci. U.S.A.

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“…3 A. The positions and the intensities of the B-site bands are again typical for an octahedral or distorted octahedral geometry [31]. The A-site MCD spectrum shows neither the typical feature of a pentacoordinate nor of a tetrahedral complex.…”

Section: And MCD Spectra Qf Co2' Containing Xyl Isomerasementioning

confidence: 92%

“…It reflects instead the intrinsic geometry of the complex. Spectra of four-, five-or six-coordinated Co(I1) complexes have been described by Kaden et al [30] and Holmquist et al [31]. Fig.…”

Section: And MCD Spectra Qf Co2' Containing Xyl Isomerasementioning

confidence: 99%

Spectroscopic studies on the metal‐ion‐binding sites of Co²⁺‐substituted D‐xylose isomerase from Streptomyces rubiginosus

Sudfeldt

Schäffer

Kägi

et al. 1990

European Journal of Biochemistry

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The coordination sphere of the two metal-binding sites/subunit of the homotetrameric D-XylOSe isomerase from Streptomyces rubiginosus has been probed by the investigation of the Co2+-substituted enzyme using electronic absorption, CD and magnetic circular dichroic spectroscopies in the visible region. The spectrum of the high-affinity site (B site) has an absorption coefficient, E~~~, of 18 M-' cm-', indicating a distorted octahedral complex geometry. The spectrum of the low-affinity site (A site) shows two absorption maxima at 505 nm and 586 nm with E values of 170 M-' cm-' and 240 M-' cm-', respectively, which indicates a distorted tetrahedral or pentacoordinated complex structure as also observed for the enzyme from Streptomyces violaceoruber [Callens et al. (1988) Biochem. J . 250, 285-2901 having the same feature but lower c values. The first 4 mol Co2+ added/ mol apoenzyme occupy both sites nearly equally. Subsequently the Co2+ located in the A site slowly moves into the B site. After equilibrium is reached, the next 4 mol Co2+/mol again occupy the A site with its typical spectrum, restoring full activity. Addition of 4 mol Cd2+ or Pb2+/mol Co4-loaded derivative displaces the Co2+ from the B site to form the Pb4/Co4 derivative containing Co2+ in the A site, reducing activity fourfold while the Pb4/Pb4 species is completely inactive. In contrast, Eu3+ displaces Co2 ' preferentially from the A site. Thus, the highand low-affinity sites may be different for different cations. After addition of the substrates D-xylose, D-glucose and D-fructose and the inhibitor xylitol the intense Co2+ A-site spectrum of both the active C04/c04 derivative and the less active Pb4/Co4 derivative decreases, indicating that these compounds are bound to the A site, changing the distorted tetrahedral or pentacoordinated symmetry there to a distorted octahedral complex geometry.The intracellular enzyme D-XylOSe isomerase is widely distributed among microorganisms like Streptomyces, Arthrohacter and Bacillus species or other bacteria [l, 21. It catalyzes in vivo the reversible isomerization of u-xylose to D-xylulose in order to utilize D-xylose from xylans as an energy source. In 1957 Marshall and Kooi [3] found that D-xylose isomerase also converts a-D-glucose into a-D-fructose. These stereospecific reactions are of industrial interest for the production of high-fructose corn syrup from starch [4] and for the conversion of hemicellulose to ethanol [5].D-Xylose isomerases from Streptomyces species exist as tetramers consisting of four identical subunits. The evaluation of X-ray crystal structures of Xyl isomerase from S. rubiginosus ATCC 21 175 [6, 71, S. olivochromogenes [8, 91 and S. rubiginosus ATCC 21 132 (previously classified as S. albus) [lo] has shown that the tetramer appears to be a dimer of dimers. This was also found for the Arthrobacter enzyme [l 11. Callens et al. [12] have shown by SDSjPAGE that treatment of the enzyme from S. violaceovuber with 0.1% SDS causes reversible dissociation into active dimers, whereas t...

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“…[el, value of -6.1 x lo-' deg cm2 dmol-' gauss-' at 19 800 cm-' (36). A positive mcd signal corresponded to E, > E, , where these are the extinction coefficients of left and right circularly polarized light respectively.…”

Section: (B) Optical Titrationsmentioning

confidence: 99%

Antitumor activity at the molecular level: binding modes in anthracycline–dinucleotide complexes as determined by optical titration and magnetic circular dichroism

Bell¹,

Buchanan²,

Hollebone³

et al. 1982

Can. J. Chem.

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. Can. J. Chem. 60,291 (1982). The first application of magnetic circular dichroism (rncd) spectroscopy to drug-dinucleotide binding is reported. The mcd spectra have been recorded for complexes of the intercalating anthracyclines carrninomycin, marcellomycin, and aclacinomycin with the dinucleotide CpG. Analysis indicates that drugs having OH groups peri to each anthraquinone carbonyl (i.e. carminomycin and marcellomycin) bind with only one drug molecule in the central hydrophilic region of the nucleotide. By contrast, aclacinomycin, in which one of the anthraquinone carbonyls lacks a peri-OH, is found to cooperatively bind, and has two drug molecules present in the dinucleotide cavity. The cooperativity of binding has been elucidated via an optical titration procedure. Chem. 60, 291 (1982). On rapporte la premiere application de la spectroscopie du dichroisme circulaire magnetique (dcm) a la liaison medicarnent-dinucleotide. On a enregistre les spectres de dcm des complexes formes par les intercalants anthracycline, carminomycine, marcellomycine et aclacinomycine, avec le dinucleotide CpG. Les analyses revelent que les medicaments qui ont des groupements OH enpPri par rapport ?+ chaque carbonyle de l'anthraquinone (comme la carminomycine et la marcellomycine) sont lies a une seule molecule de medicament dans la region hydrophile centrale du nucleotide. On trouve au contraire que I'aclacinomycine, dans laquelle il manque un groupement OH peri pour I'un des carbonyles de l'anthraquinone, est liee cooperativement et que deux moltcules de medicament sont presentes dans la cavite du dinucleotide. On a identifie la cooperativite du lien par I'intermedaire d'une methode de titration optique.[Traduit par ie journal]

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Magnetic circular dichroic spectra of cobalt(II) substituted metalloenzymes

Cited by 69 publications

References 30 publications

Metal-coordinating substrate analogs as inhibitors of metalloenzymes.

Metal-coordinating substrate analogs as inhibitors of metalloenzymes.

Spectroscopic studies on the metal‐ion‐binding sites of Co²⁺‐substituted D‐xylose isomerase from Streptomyces rubiginosus

Antitumor activity at the molecular level: binding modes in anthracycline–dinucleotide complexes as determined by optical titration and magnetic circular dichroism

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Magnetic circular dichroic spectra of cobalt(II) substituted metalloenzymes

Cited by 69 publications

References 30 publications

Metal-coordinating substrate analogs as inhibitors of metalloenzymes.

Metal-coordinating substrate analogs as inhibitors of metalloenzymes.

Spectroscopic studies on the metal‐ion‐binding sites of Co2+‐substituted D‐xylose isomerase from Streptomyces rubiginosus

Antitumor activity at the molecular level: binding modes in anthracycline–dinucleotide complexes as determined by optical titration and magnetic circular dichroism

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Spectroscopic studies on the metal‐ion‐binding sites of Co²⁺‐substituted D‐xylose isomerase from Streptomyces rubiginosus