Characterization of the nadR locus in Escherichia coli

1974 ◽  
Vol 20 (2) ◽  
pp. 205-209 ◽  
Author(s):  
Gerald J. Tritz
Keyword(s):  
Escherichia Coli ◽  
Genetic Control ◽  
Quinolinic Acid ◽  
Nicotinamide Adenine Dinucleotide ◽  
Pyridine Nucleotide ◽  
Nicotinamide Adenine ◽  
Positive Type ◽  
Pyridine Nucleotide Cycle

The biosynthesis of nicotinamide adenine dinucleotide (NAD) is under the genetic control of the nadR+ locus. The nadR+ allele is dominant to the nadR allele in transheterogenotes, indicating that the regulation is of the positive type. Mutants of the nadR type are unable to synthesize quinolinic acid; however, they do retain the ability to convert quinolinic acid into NAD and to recycle this NAD through the pyridine nucleotide cycle. Thus, the nadR+ locus regulates only genes involved in the biosynthesis of quinolinic acid.

CHARACTERIZATION OF A NICOTINAMIDE ADENINE DINUCLEOTIDE SPECIFIC NITRITE REDUCTASE FROM ESCHERICHIA COLI, STRAIN K12

1963 ◽  
Vol 9 (4) ◽  
pp. 531-539 ◽  
Author(s):  
Donald P. Zarowny ◽  
B. D. Sanwal
Keyword(s):  
Escherichia Coli ◽  
Nitrite Reductase ◽  
Nicotinamide Adenine Dinucleotide ◽  
Enzymic Activity ◽  
Coli Strain ◽  
Nicotinamide Adenine ◽  
Optimum Ph ◽  
Michaelis Constants ◽  
Reduced Nicotinamide Adenine Dinucleotide

A nitrite reductase specific for reduced nicotinamide adenine dinucleotide (NADH) was purified approximately 30-fold from Escherichia coli, strain K12. The enzyme was metal sensitive, being inhibited by certain chelating agents and stimulated by others. The optimum pH for enzymic activity was 7.8–8.0 and the Michaelis constants for nitrite and NADH were 4.0 × 10−5 moles/l, and 3.3 × 10−4 moles/l., respectively. The partially purified enzyme did not show a flavin requirement and ammonia was not the product of the enzymic reaction.

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