ZIB

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Methylamine metabolism and its role in nitrogenase “Switch off” in Rhodopseudomonas capsulata (1983)

Yoch, Duane C. ; Zhang, Zhao-ming ; Claybrook, David L.

Springer

Archives of microbiology 134 (1983), S. 45-48

add to mindlist on the mindlist

Details

ISSN: 1432-072X

Keywords: Nitrogenase ; Methylamine ; Nitrogenase switch-off ; Rhodopseudomonas capsulata

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract In the photosynthetic bacterium Rhodopseudomonas capsulata, NH 4 + switch-off of nitrogenase activity can be mimicked by its analog, methylamine. Like NH 4 + , methylamine appeared to require processing by glutamine synthetase (GS) before it was effective; γ-glutamylmethylamide was shown to be the product of this reaction. Evidence that this glutamine analog functioned directly to initiate nitrogenase inactivation was suggested first by the fact that it was a poor substrate for glutamate synthase (i.e., it was not further metabolized by this pathway) and secondly, azaserine which blocks the transfer of the glutamine amide group had no effect on CH3NH 3 + (or NH 4 + ) switch-off. These observations are taken as preliminary evidence to suggest that when NH 4 + inhibits nitrogenase activity, inactivation is initiated by glutamine itself, and not a molecule derived from it. Finally, evidence was presented that R. capsulata would use CH3NH 3 + as a nitrogen substrate, but lag periods and generation times increased with subsequent passages.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00429405

Permalink

Library	Location	Call Number	Volume/Issue/Year	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Computational studies of peripheral ring twisting in meso-N-methyl pyridyl-substituted porphyrins (1993)

Monaco, Regina R. ; Zhao, Ming

New York, NY : Wiley-Blackwell

International Journal of Quantum Chemistry 46 (1993), S. 701-709

add to mindlist on the mindlist

Details

ISSN: 0020-7608

Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Semiempirical molecular orbital calculations for the porphyrins tetrakis(4-N-methyl pyridyl)porphine (H2TMpyP-4) and tetrakis(2-N-methyl pyridyl)porphine using the MNDO and AM-1 Hamiltonians suggest that twisting one or more of the pyridinium rings results, at considerable energy expense, in highly nonplanar macrocycle configurations as the exocyclic ring(s) approach coplanarity. The results imply that the mechanism of intercalation of H2TMpyP-4 into DNA cannot require twisting the exocyclic rings anywhere close to coplanarity with the central porphine core, but involves, instead, the inherent flexibility of DNA itself. © 1993 John Wiley & Sons, Inc.

Additional Material: 10 Tab.