Factors affecting growth of Staphylococcus aureus L forms on semidefined medium

Banville, Robert R. (The Catholic University of America, Washington, D.C.). Factors affecting growth of Staphylococcus aureus L forms on semidefined medium. J. Bacteriol. 87:1192-1197. 1964.-A semidefined agar medium was found suitable for production and cultivation of the L form of Staphylococcus aureus. In semidefined liquid medium, growth of the L form took place in the form of a sediment containing large masses of cells, but heavy and diffuse growth occurred in the same medium with 0.05% agar. The optimal pH for L-colony formation on solid medium was 6.5. More L colonies developed on 0.75% agar than at higher agar concentrations. L colonies developed in greater numbers on pour plates than on streak plates, and in some cases more L colonies appeared under anaerobic incubation. L-colony formation appeared to be inhibited by sodium citrate. The vitamin requirements of the L forms studied were similar to those of the classical form.     

Characterization of a prolyl endopeptidase from Flavobacterium meningosepticum. Complete sequence and localization of the active-site serine.

A prolyl endopeptidase was purified from Flavobacterium meningosepticum. It was digested with trypsin. Two oligonucleotides, based on tryptic peptide sequences and used in PCR experiments, amplified a 300-base pair (bp) fragment. A 2.4-kilobase EcoRI fragment that hybridized to the 300-bp probe was cloned in lambda ZAP and sequenced from both strands. It contains a reading frame of 2115 bp, encoding the complete protein sequence of 705 amino acids. Ion-spray mass spectrometry experiments demonstrated the presence of an NH2-terminal signal peptide: the periplasmic mature protease is 685 residues in length for a molecular mass of 76784 Da. The prolyl endopeptidase showed no general sequence homology with known protein sequences except with that of porcine brain prolyl endopeptidase. In order to identify the active-site serine, the prolyl endopeptidase was labeled with [3H]diisopropyl fluorophosphate. One labeled peptide was purified and sequenced. The active-site serine was located in position 536 within the sequence GRSNGG. This sequence is different from the active-site sequence of the trypsin (GDSGGP) and subtilisin (GTSMAS) families.     

NMR investigation of the interaction of mithramycin A with d(ACCCGGGT)2.

The binding of mithramycin A to d(ACCCGGGT)2 has been investigated by one- and two-dimensional 1H NMR spectroscopy. Titration of the drug into the octamer solution results in loss of the oligonucleotide C2 symmetry at stoichiometric ratios less than 4 drug molecules per duplex. However, at a ratio of 4:1 (drug/duplex), the C2 symmetry of the oligonucleotide is restored. From these data it is evident that more than one complex forms at ratios less than 4:1 while only one complex predominates at the ratio 4:1. This is the first report of a DNA octamer which binds 4 large drug molecules. These results are compared to those we have recently reported for mithramycin binding to d(ATGCAT)2, where only a single, bound complex is observed, with a stoichiometry of 2:1.     

Synthesis and biological evaluation of 4-amino derivatives of benzimidazoquinoxaline, benzimidazoquinoline, and benzopyrazoloquinazoline as potent IKK inhibitors

We have recently identified BMS-345541 (1) as a highly selective and potent inhibitor of IKK-2 (IC50 = 0.30 microM), which however was considerably less potent against IKK-1 (IC50 = 4.0 microM). In order to further explore the SAR around the imidazoquinoxaline tricyclic structure of 1, we prepared a series of tetracyclic analogues (7, 13, and 18). The synthesis and biological activities of these potent IKK inhibitors are described.