TY  - JOUR
A1  - Häring, Mathias
A1  - Kerpen, Christoph
A1  - Ribbeck, Tatjana
A1  - Hennig, Philipp T.
A1  - Bertermann, Rüdiger
A1  - Ignat’ev, Nikolai V.
A1  - Finze, Maik
T1  - Dismutation of Tricyanoboryllead Compounds: The Homoleptic Tetrakis(tricyanoboryl)plumbate Tetraanion
JF  - Angewandte Chemie
N2  - A series of unprecedently air-stable (tricyanoboryl)plumbate anions was obtained by the reaction of the boron-centered nucleophile B(CN)\(_{3}\)\(^{2-}\) with triorganyllead halides. Salts of the anions [R\(_{3}\)PbB(CN)\(_{3}\)]\(^{-}\) (R=Ph, Et) were isolated and found to be stable in air at room temperature. In the case of Me\(_{3}\)PbHal (Hal=Cl, Br), a mixture of the anions [Me\(_{4-n}\)Pb{B(CN)\(_{3}\)}\(_{n}\)]\(^{n-}\) (n=1, 2) was obtained. The [Et\(_{3}\)PbB(CN)\(_{3}\)]− ion undergoes stepwise dismutation in aqueous solution to yield the plumbate anions [Et4\(_{4-n}\)Pb{B(CN)\(_{3}\)}\(_{n}\)]\(^{n-}\) (n=1–4) and PbEt\(_{4}\) as by-product. The reaction rate increases with decreasing pH value of the aqueous solution or by bubbling O\(_{2}\) through the reaction mixture. Adjustment of the conditions allowed the selective formation and isolation of salts of all anions of the series [Et\(_{4-n}\)Pb{B(CN)\(_{3}\)}\(_{n}\)]\(^{n-}\) (n=2–4) including the homoleptic tetraanion [Pb{B(CN)\(_{3}\)}\(_{4}\)]\(^{4-}\).
KW  - anions
KW  - boron
KW  - cyanoborates
KW  - dismutations
KW  - lead
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318257
VL  - 61
IS  - 24
ER  - 
TY  - JOUR
A1  - Abdali, Narges
A1  - Barth, Enrico
A1  - Norouzy, Amir
A1  - Schulz, Robert
A1  - Nau, Werner M.
A1  - Kleinekathofer, Ulrich
A1  - Tauch, Andreas
A1  - Benz, Roland
T1  - Corynebacterium jeikeium jk0268 Constitutes for the 40 Amino Acid Long PorACj, Which Forms a Homooligomeric and Anion- Selective Cell Wall Channel
JF  - PLoS ONE
N2  - Corynebacterium jeikeium, a resident of human skin, is often associated with multidrug resistant nosocomial infections in immunodepressed patients. C. jeikeium K411 belongs to mycolic acid-containing actinomycetes, the mycolata and contains a channel-forming protein as judged from reconstitution experiments with artificial lipid bilayer experiments. The channel-forming protein was present in detergent treated cell walls and in extracts of whole cells using organic solvents. A gene coding for a 40 amino acid long polypeptide possibly responsible for the pore-forming activity was identified in the known genome of C. jeikeium by its similar chromosomal localization to known porH and porA genes of other Corynebacterium strains. The gene jk0268 was expressed in a porin deficient Corynebacterium glutamicum strain. For purification temporarily histidine-tailed or with a GST-tag at the N-terminus, the homogeneous protein caused channel-forming activity with an average conductance of 1.25 nS in 1M KCl identical to the channels formed by the detergent extracts. Zero-current membrane potential measurements of the voltage dependent channel implied selectivity for anions. This preference is according to single-channel analysis caused by some excess of cationic charges located in the channel lumen formed by oligomeric alpha-helical wheels. The channel has a suggested diameter of 1.4 nm as judged from the permeability of different sized hydrated anions using the Renkin correction factor. Surprisingly, the genome of C. jeikeium contained only one gene coding for a cell wall channel of the PorA/PorH type found in other Corynebacterium species. The possible evolutionary relationship between the heterooligomeric channels formed by certain Corynebacterium strains and the homooligomeric pore of C. jeikeium is discussed.
KW  - antibiotics
KW  - detergents
KW  - anions
KW  - corynebacterium diphtheriae
KW  - membrane potential
KW  - corynebacteria
KW  - cell walls
KW  - permeability
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-129989
VL  - 8
IS  - 10
ER  -