ISSN:
0030-4921
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The proton NMR spectra of 14 actinomycins and the 13C NMR data for four of these compounds were compared with those of actinomycin D. These compounds differ from actinmycin D by the replacement of one or both proline residues by sarcosine, azetidine-2-carboxylic acid, 4-ketoproline, or cis or trans isomers of 4-hydroxy-, 4-chloro- or 4-methylproline. In those (aniso) compounds in which one proline residue is replaced, the possibility of isomerism was considered, since replacement could be located in either the α- or β-peptide. Except for the sarcosine case, for which both isomers have been isolated, the aniso-actinomycins gave spectra in which the presence of a second isomer was undetectable. Attempts to utilize the NMR data to determine which peptide contained proline, and which its congener, produced the tentative conclusion that in these compounds there is a biosynthetic preference for replacement of the β-peptide proline residue. In comparing conformationally dependent NMR parameters for the various actinomycins, the most obvious variations appeared in the proline congener α-proton splittings. Some of these (for cis isomers of 4-chloroproline and 4-methylproline) reflected different pyrrolidine ring geometries to that of proline, while others (for the corresponding trans isomers) did not. Only minor differences were apparent in the conformations of other regions of the peptide moieties.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1270170311
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