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  • 1
    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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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Polymerization of cyclohexene oxide with Al(acac)3-silanol catalyst supported by zeolite and porous silica (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 2541-2550 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of cyclohexene oxide with Al(acac)3-silanol catalyst supported by zeolite and porous silica has been investigated. Cyclohexene oxide was also polymerized to a lesser extent by a zeolite-silanol catalyst and an Al(acac)3-silica gel catalyst. The catalytic activity of the zeolite-silanol system varied with the zeolite pore size. The catalytic activity of the Al(acac)3-silanol system was enhanced by supporting the catalyst with porous silica or zeolite. The Al(acac)3-silanol catalyst supported by zeolite was especially effective in increasing polymer conversion and molecular weight. Catalytic activity increased with increasing chemical interaction between silanol and porous silica. The molecular weight of the polymers with these catalysts increased in the order zeolite-silanol〉 zeolite-Al(acac)3-silanol 〉Al(acac)3-silanol ≈ Al(acac)3-silanol supported by porous silica〉Al(acac)3-silica gel.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.170191014
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  • 4
    Electronic Resource
    Electronic Resource
    Polymerization of cyclohexene oxide with aluminum complex-silanol catalysts. Part III. Dependence of catalytic activity on bulkiness of silanol and its intramolecular hydrogen bond (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 2977-2985 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of cyclohexene oxide, especially the catalytic activity influenced by silanol structure, was examined by using an Al(acac)3-silanol compound catalyst. The catalytic activity increased as the acidity of silanol increased. It was prolonged by sterically hindered silanol compounds which prevented the silanol from self-condensation and from joining with the epoxide. In addition, the greater catalytic activity produced by intramolecular hydrogen-bonding silanol compounds is explained by the polymer effect.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.170191129
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  • 5
    Electronic Resource
    Electronic Resource
    Polymerization of cyclohexene oxide with aluminum complex-silanol catalyst. IV. Photopolymerization with Ph3SiCOPh-Al complex-alcohol catalyst system (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 1433-1443 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new catalyst system (Ph3SiCOPh-aluminum complex-alcohol) was investigated for photopolymerization of cyclohexene oxide. Polymer conversion and molecular weight increased with polymerization time. When a Ph3SiCOPh-Al (n-Praa)3-alcohol catalyst system was used the catalyst activity decreased, depending on the alcohol: i-PrOH 〉 n-PrOH 〉 i-BuOH 〉 MeOH 〉 t-BuOH 〉 H2O. When the Ph3SiCOPh-Al complex-i-PrOH catalyst system was used the catalyst activity decreased, depending on the ligand of the Al complex: ß-ketoester 〉 orthocarbonyl phenol 〉 ß-diketone. Benzophenone derivatives were effective for catalyst activation as a photosensitizer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170200606
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  • 6
    Electronic Resource
    Electronic Resource
    Polymerization of cyclohexene oxide with Al(acac)3- silanol catalyst (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 2185-2194 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of cyclohexene oxide was investigated with a new catalyst system of Al(acac)3- silanol compounds. Catalyst activity varied with the ratio of silanol/Al(acac)3 and the structure of silanol compounds. Catalyst deactivation appeared to be caused by self-condensation of silanol and the addition of silanol to the epoxy ring. Polymer structure was investigated by 13C-NMR spectroscopy and x-ray diffraction. The mechanism of the polymerization appears to be cationic.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.170190906
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  • 7
    Electronic Resource
    Electronic Resource
    Polymerization of cyclohexene oxide with aluminum complex/silanol catalysts. V. A catalytic activity dependence on the aluminum chelate structure (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 3155-3165 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The catalytic activity of an aluminum complex/silanol system was found to vary with the aluminum ligand as follows: β-diketonate 〈 β-ketoester anion 〈 ortho-carbonylphenolate. Aluminum complexes with electron donating groups conjugated with a carbonyl group had higher catalytic activity. The catalyst activity correlated with the strength of interaction between the aluminum complex and the silanol; there were two such interaction mechanisms. Cyclohexene oxide was polymerized cationically by the activated proton of SiOH. The activated proton is considered to be similar to Brönsted acid on silica-alumina catalyst; therefore, the catalyst would be a model of the silica-alumina catalyst.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170201111
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  • 8
    Electronic Resource
    Electronic Resource
    Polymerization of cyclohexene oxide with Al(acac)3-silanol catalyst (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 1652-1652 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170200627
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