Nocardia mediterranei produces the antibiotic rifamycin B, which belongs to the ansamycin group. The structure of rifamycin consists of the ansa chain and the chromophore. One part of this chromophore, the seven-carbon amino unit, which initiates ansa chain formation in ansamycins, has been identified as 3-amino-5-hydroxybenzoic acid. Kibby et al. 1] synthesized [carboxy-14C]3-amino-5hydroxyben...

Escherichia coli contains two L-asparaginase isozymes: L-asparaginase I, a low-affinity enzyme located in the cytoplasm, and L-asparaginase II, a high-affinity secreted enzyme. A molecular genetic analysis of the gene (ansA) encoding the former enzyme has previously been reported. We now present a molecular study of the gene, ansB, encoding L-asparaginase II. This gene was isolated by using oli...

Stimulation of discrete intracardiac sympathetic nerves to the SA (SAS stimulation) or AV nodal region (AVS stimulation) increased the heart rate or decreased AV conduction time and caused an AV junctional rhythm, respectively, in anesthetized dogs treated with atropine. Topical application of tetrodotoxin (TTX) at the SAS or AVS stimulation locus totally inhibited the response to each stimulat...

The title compound, [Mo(4)(C(16)H(20))(2)O(8)]·6H(2)O, is a centrosymmetric ansa-molybdocene complex in which two dinuclear [C(2)Me(4)(η(5)-C(5)H(4))(2)]Mo(μ(2)-O)(2)MoO(2) units dimerize by forming two μ(3)-O bridges between three Mo atoms. The ansa-molybdocene [C(2)Me(4)(η(5)-C(5)H(4))(2)]Mo unit has a typical bent-sandwich metallocene structure with an inter-ring angle of 127.98 (8)°. The Mo...

Ansa-bridged prodiginines are bioactive pigments produced by bacteria. Certain of these structures are reported to be antagonists of protein-protein interactions involved in apoptosis. We describe a new entry to alkaloids of this type, demonstrated with a concise asymmetric synthesis of (+)-roseophilin (3). Our route constructs the pyrrolophane motif via phosphoryl transfer-terminated macroaldo...

Reaction of (ClMe2SiC5H4)2ZrCl2 (1) with K (Na) in liquid ammonia/toluene at -78 °C gave the ansa-zirconocene dihydride [{HN(SiMe2C5H4)2Zr(μH)H}2] (3). Alternatively, treatment of (MeC5H4)2ZrCl2 (2) with K (Na) or NaNH2 in liquid ammonia/toluene produced the zirconium cluster [{(MeC5H4)Zr}5(μ5-N)(μ3-NH)4(μ-NH2)4] (4). The reaction of 2 with NaNH2 in THF led also to the formation of 4.

Many models are complex systems comprised of numerous different sub models. These sub models could be subjected to different load types, i.e. long duration or short duration, which would be better treated using a different type of discretization techniques and solution algorithms [1]. This problem can be addressed by Co-simulation which is the coupling of different simulation systems that excha...