Distance determinations between the metal ion sites of Escherichia coli glutamine synthetase by electron paramagnetic resonance using chromium(III)-nucleotides as paramagnetic substrate analogs

Biochemistry ◽  
1978 ◽  
Vol 17 (17) ◽  
pp. 3531-3538 ◽  
Author(s):  
M. S. Balakrishnan ◽  
Joseph J. Villafranca
Keyword(s):  
Escherichia Coli ◽  
Electron Paramagnetic Resonance ◽  
Glutamine Synthetase ◽  
Metal Ion ◽  
Paramagnetic Resonance ◽  
Substrate Analogs ◽  
Electron Paramagnetic

Dense-shell glycodendrimers: UV/Vis and electron paramagnetic resonance study of metal ion complexation

2009 ◽  
Vol 466 (2117) ◽  
pp. 1489-1513 ◽  
Author(s):  
Dietmar Appelhans ◽  
Ulrich Oertel ◽  
Roberto Mazzeo ◽  
Hartmut Komber ◽  
Jan Hoffmann ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Metal Ion ◽  
Electron Paramagnetic Resonance Study ◽  
Copper Metabolism ◽  
Paramagnetic Resonance ◽  
Fifth Generation ◽  
Vis Spectroscopy ◽  
Dense Shell ◽  
Biological Environment ◽  
Electron Paramagnetic

The development of dendritic metal ion carrier systems for use in a biological environment is a challenging task as the carrier system must possess multiple features (e.g. a protective shell for metal decomplexation, targeting functions, metal–intradendrimer complexes, etc.) to substitute for the function of metal proteins in processes such as copper metabolism. Thus, Cu(II) complexation by a series of poly(propyleneimine) glycodendrimers ranging up to the fifth generation that have either a dense maltose or maltotriose shell was investigated by UV/Vis spectroscopy and electron paramagnetic resonance (EPR). As a necessary step towards potential biological application, we elucidated the complexation capacity, location of the Cu(II)–dendrimer complexes and the Cu(II) coordination sphere in the dendritic environment. A generation-dependent Cu(II) complexation was found. Furthermore, analysis of the EPR spectra revealed that internal and external Cu(II) coordination and the symmetry (axial and rhombic) of the generated complexes depend on the oligosaccharide shell, dendrimer generation and the relative concentrations of Cu(II) and the dendrimers. Both axial and rhombic symmetries are generation dependent, but also distort with increasing generation number. External coordination of Cu(II) is supported by sugar groups and water molecules. Finally, a third-generation dendrimer with a maltose shell was used to explore the general complexation behaviour of the dendritic poly(propyleneimine) scaffold towards different metal ions [Cu(II), Ag(I), VO(IV), Ni(II), Eu(III) and UO 2 (VI)].

Interaction of selectively spin-labeled 70S ribosomes with tRNAPhe. An electron paramagnetic resonance study

1981 ◽  
Vol 59 (5) ◽  
pp. 311-314 ◽  
Author(s):  
Angel Rodriguez ◽  
Hermann Dugas
Keyword(s):  
Escherichia Coli ◽  
Electron Paramagnetic Resonance ◽  
Structural Change ◽  
Ribosomal Proteins ◽  
Electron Paramagnetic Resonance Study ◽  
Paramagnetic Resonance ◽  
Trna Molecule ◽  
Sh Groups ◽  
Ribosome Structure ◽  
Electron Paramagnetic

70S ribosomes from Escherichia coli, selectively spin labeled on the SH groups of proteins S18, S12, S21, S17, and L27, were used to study the formation of the tertiary complex ribosome–poly(U)–tRNAPhe. Most of these ribosomal proteins are located in the region of binding of tRNA. The electron paramagnetic resonance observable structural change suggests a loosening of the ribosome structure upon binding of the tRNA molecule.

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