首页 | 本学科首页   官方微博 | 高级检索  
   检索      


Evidence of a quinoprotein glucose dehydrogenase apoenzyme in several strains of Escherichia coli
Authors:RWJ Hommes  PW Postma  OM Neijssel  DW Tempest  P Dokter  JA Duine
Institution:Laboratory of Microbiology, University of Amsterdam, P.O. Box 20245, 1000 HE Amsterdam The Netherlands;Laboratory of Biochemistry, University of Amsterdam, P.O. Box 20245, 1000 HE Amsterdam The Netherlands;Laboratory of Biochemistry, Delft University of Technology, Delft, The Netherlands
Abstract:Abstract When grown on glucose in K+-limited chemostat culture, or in batch culture with or without 2,4-dinitrophenol, several strains of Escherichia coli (including the type strain) were found to synthesize a quinoprotein glucose dehydrogenase apoenzyme. The pyridine nucleotides, NAD+ and NADP+, would not serve as cofactor, but activity could be demonstrated upon addition of 2,7,9-tricarboxy-1 H -pyrrolo(2,3- f )quinoline-4,5-dione (PQQ). Thus, in the presence of PQQ, but not in its absence, glucose was oxidized to gluconic acid. A mutant of E. coli PC 1000 was isolated that lacked Enzyme I of the phospho enol pyruvate phosphotransferase system (PTS) but still synthesized the glucose dehydrogenase apoenzyme. Whereas this mutant would not grow on glucose in the absence of PQQ, it would do so in the presence of low concentrations (1 μM) of this cofactor. On the basis of these observations, it is concluded that the protein (apoenzyme) formed is a genuine glucose dehydrogenase, but that it is not functional in growing cells due to their inability to synthesize the appropriate cofactor (PQQ), at least under these conditions.
Keywords:Glucose dehydrogenase  pyrrolo-quinoline quinone              Escherichia coli
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号