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  • 1
    Electronic Resource
    Electronic Resource
    Spectroscopic and electrochemical properties of two azurins (Az-iso1 and Az-iso2) from the obligate methylotroph Methylomonas sp. strain J and the structure of novel Az-iso2 (1999)
    Springer
    JBIC 4 (1999), S. 749-758 
    Details
    ISSN: 1432-1327
    Keywords: Azurin ; Methylamine dehydrogenase ; Blue copper protein ; Obligate methylotroph ; X-ray crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Methylomonas sp. strain J gives rise to two azurins (Az-iso1 and Az-iso2) with methylamine dehydrogenase (MADH-Mj). The intense blue bands characteristic of Az-iso1 and Az-iso2 are observed at 621 and 616 nm in the visible absorption spectra respectively, being revealed at 620−630 nm in those of usual azurins. The EPR signal of Az-iso1, similar to usual azurins, shows axial symmetry, while the axial EPR signal of Az-iso2 involves a slightly rhombic character. The half-wave potentials (E 1/2) of the two azurins and the intermolecular electron-transfer rate constants (k ET) from MADH-Mj to each azurin were determined by cyclic voltammetry. The E 1/2 values of Az-iso1 and Az-iso2 are +321 and +278 mV vs NHE at pH 7.0, respectively. The k ET value of Az-iso2 is larger than that of Az-iso1 by a factor of 5. However, the electron-transfer rate of Az-iso2 is interestingly slower than those of the azurins from a denitrifying bacterium, Alcaligenes xylosoxidans NCIB 11015, and the amicyanin from a different methylotroph, Methylobacterium extorquens AM1. The structure of Az-iso2 has been determined and refined against 1.6 Å X-ray diffraction data. The whole structure of Az-iso2 is quite similar to those of azurins reported already. The Cu(II) site of Az-iso2 is a distorted trigonal bipyramidal geometry like those of other azurins, but some of the Cu-ligand distances and ligand-Cu-ligand bond angle parameters are slightly different. These findings suggest that Az-iso2 is a novel azurin and perhaps functions as an electron acceptor for MADH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010653
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  • 2
    Electronic Resource
    Electronic Resource
    Spectroscopic characterization of native and Co(II)-substituted zucchini mavicyanin (1997)
    Springer
    JBIC 2 (1997), S. 177-181 
    Details
    ISSN: 1432-1327
    Keywords: Key words Mavicyanin ; Blue copper protein ; Cobalt(II) substitution ; Magnetic circular dichroism spectrum ; Resonance Raman spectrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  Mavicyanin from zucchini peelings has been characterized by electronic absorption, circular dichroism (CD), magnetic circular dichroism (MCD), resonance Raman (RR), and electron paramagnetic resonance (EPR) spectra. The electronic absorption, CD, MCD, and EPR spectra are appreciably similar to those of stellacyanin from lacquer, in which the tetrahedral Cu center has a donor set composed of four amino acid residues [2 histidine (His), cysteine (Cys), and glutamine (Gln)]. Under neutral conditions, mavicyanin and stellacyanin show intense blue bands at 599 and 604 nm, respectively. However, the RR spectrum of mavicyanin between 300 and 450 cm–1, which is believed to originate from the predominant Cu–S stretching vibration, is remarkably different from that of stellacyanin. This might be due to a slight distortion of the tetrahedral Cu(II) center toward tetragonal geometry in mavicyanin. Moreover, the d–d transition bands of Co(II)-substituted mavicyanin are slightly blue-shifted compared with those of Co(II)-substituted stellacyanin. This finding also suggests a difference in distortion between these tetrahedral Co(II) centers in spite of the same donor sets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050122
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