Kevin Michel

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The structure of antibiotic A33853, isolated from the culture broth of Streptomyces sp., NRRL 12068, is reported. The structure was deduced from an X-ray crystallographic study of its tetraacetyl derivative. Tetraacetyl A33853 is unique because it contains an anhydride moiety, an unexpected product from the reaction of A33853 with acetic anhydride and(More)
The antifungal antibiotic, echinocandin B (ECB), was modified by a sequential procedure in which the initial step involved enzymatic removal of the native N-linoleoyl group from the N-terminus using an Actinoplanes utahensis culture. The resulting product, ECB nucleus, was reacylated using active esters or acid halides of various substituted acids to give a(More)
A novel group of antibiotics, comprising microbiologically-active structurally-related factors A25822A, B, D, H, L, M and N, produced by culturing Geotrichum flavo-brunneum NRRL 3862 under submerged aerobic fermentation conditions was isolated by extraction. The individual factors were separated and purified by chromatography and crystallization. The major(More)
The confinement of a C60 molecule encapsulated in a cylindrical nanotube depends on the tube radius. In small tubes with radius RT approximately < 7 A, a fivefold axis of the molecule coincides with the tube axis. The interaction between C60 molecules in the nanotube is then described by a O2-rotor model on a 1D liquid chain with coupling between(More)
The superposition of the quantum rotational motion (tunneling) of the encapsulated Sc(2)C(2) complex with the classical rotational motion of the surrounding C(84) molecule in a powder crystal of Sc(2)C(2)@C(84) fullerite is investigated by theory. Since the quantum rotor is dragged along by the C(84) molecule, any detection method which couples to the(More)