Ligand Abstraction in the Reaction of Aryldiazonium Ions with some Iron Complexes Containing Coordinated Cysteine, Maleonitriledithiol, or Triarylphosphine

1974 ◽  
Vol 52 (10) ◽  
pp. 1914-1922 ◽  
Author(s):  
James A. Carroll ◽  
David R. Fisher ◽  
Geoffrey W. Rayner Canham ◽  
Derek Sutton
Keyword(s):  
Nitrogen Fixation ◽  
Raman Spectra ◽  
Biological Nitrogen Fixation ◽  
Iron Complexes ◽  
Detailed Comparison ◽  
A Site ◽  
Biological Nitrogen ◽  
Extrusion Product

The reactions of selected aryldiazonium tetrafluoroborates with Fe(CO)3(PR3)2, [Fe(mnt)2]−, [Fe(cystH)2]2+, and [Fe(CO)2(cyst)2] (mnt = S2C2(CN)2, cyst = SCH2CH(NH2)CO2H ) result in abstraction of the ligand to yield arenediazophosphonium ions, S-(arenediazo)cysteine or the dinitrogen extrusion product ArS(CN)C=C(CN)SAr. Arylazo complexes of iron were not obtained. The products have been characterized and compounds related to S-(arenediazo)cysteine, namely S-(arenediazo)triphenylmethyl mercaptan and S-(arenediazo)sulfones, have been synthesized for a detailed comparison of their Raman spectra. Assignments of ν(N=N) are made on the basis of 15N- and 2H-substitution experiments. The possible involvement of nucleophilic sulfur as a site for the activation and or reduction of complexed dinitrogen in biological nitrogen fixation is proposed.

scholarly journals Potential Impacts of Changing Precipitation Patterns on Biological Nitrogen Fixation in Soybean (Glycine Max L.) as Mediated by Landscape Position and Tillage

2021 ◽  
Author(s):  
Kathryn Glanville ◽  
G. Philip Robertson
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Conventional Tillage ◽  
Landscape Position ◽  
N Transformations ◽  
Legume Crop ◽  
No Till ◽  
Rainfall Patterns ◽  
A Site ◽  
Biological Nitrogen

Abstract PurposeExpected changes in rainfall patterns will affect the timing of N-mineralization and other N transformations, potentially promoting or suppressing biological nitrogen fixation (BNF). We test the hypotheses that BNF is more sensitive to changing rainfall patterns in summit vs. toeslope positions and in till vs. no-till consistent with patterns of soil texture and organic matter.MethodsAt a site in the upper Midwest USA, we measured soybean BNF 15N natural abundance at different landscape positions with and without supplemental rainfall and in till vs. no-till rainfall exclusion shelters to lengthen the dry periods between rainfall events. ResultsSoybean BNF was 41% higher at summit than toeslope positions, consistent with lower soil OM and coarser texture at summits. When precipitation was increased by 20%, BNF decreased at summit positions and was unaffected at toeslope positions. In a separate tillage experiment, with 3-week (but not 2-week) rainfall intervals, %BNF decreased 15% under conventional tillage and increased 14% under no-till. ConclusionsChanging rainfall patterns affected BNF differentially depending on landscape position and tillage in well-drained Alfisols. BNF was greater in summit than in toeslope positions and decreased with added rainfall. BNF under conventional tillage was more sensitive to longer rainfall intervals than was BNF under no-till. Models that incorporate these interactions will be better able to characterize legume crop performance and N use across landscapes and improve global estimates for BNF.

scholarly journals Functional analysis of multiple nifB genes of Paenibacillus strains in synthesis of Mo-, Fe- and V-nitrogenases

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Qin Li ◽  
Haowei Zhang ◽  
Liqun Zhang ◽  
Sanfeng Chen
Keyword(s):  
Functional Analysis ◽  
Nitrogen Fixation ◽  
Gene Cluster ◽  
Biological Nitrogen Fixation ◽  
Deletion Analysis ◽  
Phylogeny Analysis ◽  
Biological Nitrogen

Abstract Background Biological nitrogen fixation is catalyzed by Mo-, V- and Fe-nitrogenases that are encoded by nif, vnf and anf genes, respectively. NifB is the key protein in synthesis of the cofactors of all nitrogenases. Most diazotrophic Paenibacillus strains have only one nifB gene located in a compact nif gene cluster (nifBHDKENX(orf1)hesAnifV). But some Paenibacillus strains have multiple nifB genes and their functions are not known. Results A total of 138 nifB genes are found in the 116 diazotrophic Paenibacillus strains. Phylogeny analysis shows that these nifB genes fall into 4 classes: nifBI class including the genes (named as nifB1 genes) that are the first gene within the compact nif gene cluster, nifBII class including the genes (named as nifB2 genes) that are adjacent to anf or vnf genes, nifBIII class whose members are designated as nifB3 genes and nifBIV class whose members are named as nifB4 genes are scattered on genomes. Functional analysis by complementation of the ∆nifB mutant of P. polymyxa which has only one nifB gene has shown that both nifB1 and nifB2 are active in synthesis of Mo-nitrogenase, while nifB3 and nifB4 genes are not. Deletion analysis also has revealed that nifB1 of Paenibacillus sabinae T27 is involved in synthesis of Mo-nitrogenase, while nifB3 and nifB4 genes are not. Complementation of the P. polymyxa ∆nifBHDK mutant with the four reconstituted operons: nifB1anfHDGK, nifB2anfHDGK, nifB1vnfHDGK and nifB2vnfHDGK, has shown both that nifB1 and nifB2 were able to support synthesis of Fe- or V-nitrogenases. Transcriptional results obtained in the original Paenibacillus strains are consistent with the complementation results. Conclusions The multiple nifB genes of the diazotrophic Paenibacillus strains are divided into 4 classes. The nifB1 located in a compact nif gene cluster (nifBHDKENX(orf1)hesAnifV) and the nifB2 genes being adjacent to nif or anf or vnf genes are active in synthesis of Mo-, Fe and V-nitrogenases, but nifB3 and nifB4 are not. The reconstituted anf system comprising 8 genes (nifBanfHDGK and nifXhesAnifV) and vnf system comprising 10 genes (nifBvnfHDGKEN and nifXhesAnifV) support synthesis of Fe-nitrogenase and V-nitrogenase in Paenibacillus background, respectively.

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