CONTRIBUTION OF MASS-SPECTROMETRY TO THE STRUCTURAL CONFIRMATION OF COMPONENTS OF THE ANTIBIOTIC GE2270 COMPLEX

The GE2270 complex consists mainly of GE2270 A (MW 1289), a thiazolyl peptide antibiotic whose structure originates from the modification of a chain of 14 amino acids in a process which creates six thiazole rin gs and one pyridine. Together with the main component, a number of str ucturally related molecules are co-produced in small quantities by fer mentation. A preparative high-performance liquid chromatrography metho d was developed to isolate GE2270 factors B-1, B-2, C-1, C-2a, C-2b, D -1, D-2, E and T. Their structures, preliminarily determined by H-1-nu clear magnetic resonance spectroscopy in comparison with GE2270 A, wer e confirmed by low and high resolution fast-atom bombardment mass spec trometry and studies on the intact molecules and on their main hydroly sis products. Their molecular weights range from 1246 to 1306 Da. The structural differences between the factors lie in the extent of methyl ation and/or oxidation of thiazole rings (D and E) and asparagine, and in the aromatization of the oxazoline ring.