Document Detail

Purification and further characterization of the second nitrate reductase of Escherichia coli K12.
MedLine Citation:
PMID:  2139607     Owner:  NLM     Status:  MEDLINE    
Two nitrate reductases, nitrate reductase A and nitrate reductase Z, exist in Escherichia coli. The nitrate reductase Z enzyme has been purified from the membrane fraction of a strain which is deleted for the operon encoding the nitrate reductase A enzyme and which harbours a multicopy plasmid carrying the nitrate reductase Z structural genes; it was purified 219 times with a yield of about 11%. It is an Mr-230,000 complex containing 13 atoms iron and 12 atoms labile sulfur/molecule. The presence of a molybdopterin cofactor in the nitrate reductase Z complex was demonstrated by reconstitution experiments of the molybdenum-cofactor-deficient NADPH-dependent nitrate reductase activity from a Neurospora crassa nit-1 mutant and by fluorescence emission and excitation spectra of stable derivatives of molybdoterin extracted from the purified enzyme. Both nitrate reductases share common properties such as relative molecular mass, subunit composition and electron donors and acceptors. Nevertheless, they diverge by two properties: their electrophoretic migrations are very different (RF of 0.38 for nitrate reductase Z versus 0.23 for nitrate reductase A), as are their susceptibilities to trypsin. An immunological study performed with a serum raised against nitrate reductase Z confirmed the existence of common epitopes in both complexes but unambiguously demonstrated the presence of specific determinants in nitrate reductase Z. Furthermore, it revealed a peculiar aspect of the regulation of both nitrate reductases: the nitrate reductase A enzyme is repressed by oxygen, strongly inducible by nitrate and positively controlled by the fnr gene product; on the contrary, the nitrate reductase Z enzyme is produced aerobically, barely induced by nitrate and repressed by the fnr gene product in anaerobiosis.
C Iobbi-Nivol; C L Santini; F Blasco; G Giordano
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  European journal of biochemistry / FEBS     Volume:  188     ISSN:  0014-2956     ISO Abbreviation:  Eur. J. Biochem.     Publication Date:  1990 Mar 
Date Detail:
Created Date:  1990-06-01     Completed Date:  1990-06-01     Revised Date:  2007-07-23    
Medline Journal Info:
Nlm Unique ID:  0107600     Medline TA:  Eur J Biochem     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  679-87     Citation Subset:  IM    
Centre National de la Recherche Scientifique, Laboratoire de Chimie Bactérienne, Marseille, France.
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MeSH Terms
Enzyme Activation / drug effects
Escherichia coli / enzymology*,  genetics
Gene Expression Regulation, Bacterial
Gene Expression Regulation, Enzymologic
Iron-Sulfur Proteins / isolation & purification
Metalloproteins / isolation & purification
Neurospora crassa / metabolism
Nitrate Reductases / genetics,  immunology,  isolation & purification*
Nitrates / pharmacology
Precipitin Tests
Pteridines / isolation & purification
Spectrometry, Fluorescence
Subcellular Fractions / enzymology
Reg. No./Substance:
0/Coenzymes; 0/Iron-Sulfur Proteins; 0/Metalloproteins; 0/Nitrates; 0/Pteridines; 73508-07-3/molybdenum cofactor; EC 1.7.-/Nitrate Reductases; EC

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