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Xanthocillin precursors

The hazimycins appear to be derived by simple coupling of two tyrosine residues ortho to the hydroxyl groups. Again the origin of the isonitrile function is unclear. In contrast to the situation for xanthocillins, [Me- CJ-methionine did act as a precursor, albeit considerably less efficiently than tyrosine and feeding of the C-labelled compound proved that the methyl group labelled the isonitrile function. Thus formation of the latter by oxidation of a N-methyl group seemed likely but, inconsistently with this, no label... [Pg.716]

Xanthocillin (134) is a yellow antibiotic pigment produced by cultures of Penicillium notatum. A novel structural feature , which is of considerable interest from the biogenetic point of view, is the presence of the isonitrile grouping. Because of its symmetrical structure, it has been assumed that the xanthocillin molecule is formed by union of two biogenetically equivalent precursors and tracer experiments performed by Achenbach and Grisebach showed that the Cg.C2 unit was most probably derived from tyrosine. Thus d L-2-[ C]-tyrosine was incorporated into the antibiotic in high yield (25 per cent) and the position of the isotopic label determined by degradation to the a-diketone (135) and anisic... [Pg.175]

Because of its symmetrical structure it is supposed that xanthocillin may originate by radical bonding of two biogenetically equivalent precursors. These precursors could be derived from the amino acid tyrosine. It is difficult to formulate a plausible biogenetic scheme for the formation of the isonitrile groups on the basis of any known biogenetic pathways. [Pg.26]

Tracer experiments were performed to elucidate the biogenesis of xanthocillin (Achenbach and Grisebach, 1965). Tablet shows the incorporation of from radioactive precursors. [Pg.26]

The extremely high incorporation of tyrosine-2- C into xanthocillin establishes this amino acid as a precursor. During this process the carboxyl group of t5n osine must be lost as is shown by the experiment with tyrosine-1- C. Further evidence was given by chemical degradation of the radioactive xanthocillin after incorporation of tyrosine-2- C (Fig. 2). [Pg.27]

To investigate the origin of the isonitrile carbon atoms, radioactive substances known to be Cj-precursors were added to xanthocillin-producing cultures. Surprisingly, there was no radioactivity incorporated either from methionine- CHg or from formate- C, a result which indicates that the isonitrile carbons do not... [Pg.27]


See other pages where Xanthocillin precursors is mentioned: [Pg.715]    [Pg.716]    [Pg.716]    [Pg.254]    [Pg.178]    [Pg.28]   
See also in sourсe #XX -- [ Pg.27 ]




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