Results 181 to 190 of about 3,727 (217)
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The PQQ-alcohol dehydrogenase of Gluconacetobacter diazotrophicus
International Journal of Food Microbiology, 2008The oxidation of ethanol to acetic acid is the most characteristic process in acetic acid bacteria. Gluconacetobacter diazotrophicus is rather unique among the acetic acid bacteria as it carries out nitrogen fixation and is a true endophyte, originally isolated from sugar cane. Aside its peculiar life style, Ga. diazotrophicus, possesses a constitutive
Saúl, Gómez-Manzo +5 more
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The Chemistry and Biomimetics of PQQ
1989Chemical simulation of redox functions of PQQ-containing enzymes was studied to clarify the roles of coenzyme PQQ. Thus catalytic oxidations of amines, amino acids, glucose, alcohols, thiols, and nitroalkanes with PQQ were investigated from the stand point of organic chemistry and effective redox system was found as oxidase models.
Yoshiki Ohshiro, Shinobu Itoh
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1989
A new method for gas chromatographic analysis of PQQ is presented. A sample was made weakly-alkaline and passed through a Sep-Pak C18 cartridge. The eluate was then made acid with HCl and passed through the second Sep-Pak C18 cartridge. Finally, PQQ was eluted with pyridine solution; it was evaporated to dryness.
O. Suzuki +4 more
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A new method for gas chromatographic analysis of PQQ is presented. A sample was made weakly-alkaline and passed through a Sep-Pak C18 cartridge. The eluate was then made acid with HCl and passed through the second Sep-Pak C18 cartridge. Finally, PQQ was eluted with pyridine solution; it was evaporated to dryness.
O. Suzuki +4 more
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Identification and Quantification of PQQ
1989PQQ can occur in free form, as a C5-addition compound, as a condensation product with amino acids (e.g. an oxazole) and in an extractable or covalently bound form. Free, underivatized PQQ can be quantified by several chromatographic methods and biological assays. However, alternative analytical procedures had to be developed for the other cases. The so-
Robert A. van der Meer +2 more
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Mutants of Methylobacterium organophilum Unable to Synthesize PQQ
Antonie van Leeuwenhoek, 1989The phenotype of mutants unable to synthesize PQQ is analyzed for different categories of methylotrophic bacteria. The advantages offered by strains dissimilating methylamine through methylated amino-acids are discussed. In M.organophilum, 40% of the mutants unable to grow in methanol medium but with normal methylamine utilization, were affected in PQQ
F, Biville +3 more
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The reaction of coenzyme PQQ with hydrazines
Journal of the Chemical Society, Perkin Transactions 2, 1990The reaction of coenzyme PQQ with hydrazines, which are known to be inhibitors of quinoprotein amine oxidases, has been investigated in vitro. Only the redox reaction is observed in the reaction with phenylhydrazine, methylhydrazine,N,N-dimethylhydrazine, and N, N′-dimethylhydrazine.
Minae Mure +4 more
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Pyrroloquinoline Quinone (PQQ) and Quinoprotein Enzymes
Antioxidants & Redox Signaling, 2001This review summarises the characteristics, identification, and measurement of pyrroloquinoline quinone, the prosthetic group of bacterial quinoprotein dehydrogenases whose structures, mechanisms, and electron transport functions are described in detail. Type I alcohol dehydrogenase includes the "classic" methanol dehydrogenase; its x-ray structure and
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Biochemical and Biophysical Research Communications, 1988
Porcine kidney diamine oxidase, a PQQ-enzyme, can be directly measured by formazan production with putrescine and nitroblue tetrazolium. This cyclic reaction in air is unaffected by superoxide dimutase, suggesting a two electron transfer between substrate-reduced PQQ-locus and nitroblue tetrazolium, without intermediate formation of superoxide.
M A, Paz +3 more
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Porcine kidney diamine oxidase, a PQQ-enzyme, can be directly measured by formazan production with putrescine and nitroblue tetrazolium. This cyclic reaction in air is unaffected by superoxide dimutase, suggesting a two electron transfer between substrate-reduced PQQ-locus and nitroblue tetrazolium, without intermediate formation of superoxide.
M A, Paz +3 more
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PQQ and quinoproteins: An important novel field in enzymology
Antonie van Leeuwenhoek, 1989In view of the landmark attained with the first International Symposium on PQQ and Quinoproteins, it seemed a good opportunity to use the present contribution to evaluate the relevance of this topic for enzymology and related scientific disciplines.
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Biochemistry of Vitamin B6 and PQQ
1994History of Vitamin B6.- Molecular evolution.- Molecular evolution of pyridoxal-5'-phosphate-dependent enzymes.- Stereospecificity of aminotransferases for C-4' hydrogen transfer and enzyme evolution.- Detection of weak structural similarities among PLP dependent enzymes.- Aminotransferases.- Crystallographic studies on the Vitamin B6-assisted enzymic ...
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