Fig. 1.

Structure of GE81112. The structure, determined by NMR spectroscopy (A. Lazzarini, L.B., L. Cavalletti, M. Abbondi, E. Corti, I. Ciciliato, L. Gastaldo, A. Marazzi, M. Feroggio, A. Maio, et al., unpublished data), consists of four amino acids (3-hydroxypipecolic acid, 2-amino-5-[(aminocarbonyl)oxy]-4-hydroxypentanoic acid, histidine, and 5-chloro-2-imidazolylserine). Three forms of GE81112 having molecular masses between 643 and 658 Da have been identified; factor B is shown in the figure with the alternative substituents of the other factors (indicated in the parentheses) present in the corresponding positions of the molecule.