1,2-Diamine derivatives are valuable building blocks to heterocyclic compounds and important precursors of biologically relevant compounds. In this respect, amino acid-derived β-keto esters are a suitable starting point for the synthesis of β,γ-diamino ester derivatives through a two-step reductive amination procedure with either simple amines or α-amino esters. AcOH and NaBH(3)CN are the addit...

The title bis-piperidine, C26H28N2O3, was unexpectedly obtained via a dimerization mechanism promoted by acetic acid when performing the Dieckmann cyclization of a chiral amido ester. The S,S configuration was assigned by reference to the enanti-omerically pure starting material. In the mol-ecule, two core heterocycles are linked by a σ bond. One ring includes a keto-enol group, while the other...

F13459 is a new inhibitor of synthesis and trafficking of virus glycoprotein isolated from the culture broth of a Penicillium sp. The molecular formula of F13459 was determined to be C27H28O11 by HRFAB-MS and NMR spectral analyses. The structure of F13459 was elucidated to be 3,4-dihydro-3,4,6,8-tetrahydroxy-3-methyl-1H-2-benzopyran-1-one 4-O-mycophenolate, an ester derivative of mycophenolic a...

Desulfovibrio desulfuricans anaerobes are constituents of human alimentary tract microflora. There are suggestions that they take part in the pathogenesis of periodontitis and some gastrointestinal inflammatory disorders, such as ulcerative colitis or Crohn's disease. Endotoxin is one of Gram-negative bacteria cellular components that influence these microorganisms pathogenicity. Endotoxin is a...

The regulation of the branched chain alpha-keto acid dehydrogenase multienzyme complex was investigated in the isolated, perfused rat liver. The metabolic flux through the branched chain alpha-keto acid dehydrogenase was monitored by measuring the production of 14CO2 from infused 1-14C-labeled branched chain alpha-keto acid substrates. The rate of decarboxylation of alpha-keto[1-14C]isocaproate...

The enzyme, 2-keto-3-deoxy-6-phosphogluconic aldolase is inactivated by the substrate analog, bromopyruvate. Inactivation results from either an active site carboxyl group or a cysteine being alkylated by bromopyruvate. Treatment of enzyme inactivated by carboxylate ester formation with borohydride produces the secondary amine resulting from reduction of a Schiff’s base between the covalently f...

Despite the apparent similarity between the plant Photosystem II reaction center (RC) and its purple bacterial counterpart, we show in this work that the mechanism of charge separation is very different for the two photosynthetic RCs. By using femtosecond visible-pump-mid-infrared probe spectroscopy in the region of the chlorophyll ester and keto modes, between 1,775 and 1,585 cm(-1), with 150-...