OXYGEN-18 AND FLUOROPROLINE STUDIES ON SYNTHESIS OF HYDROXYPROLINE AND OXOPROLINE IN ACTINOMYCIN

Investigations have been carried out with 18O2 and H218O to determine the source of oxygen incorporated into the hydroxyl group of 4-hydroxy-l-proline and the carbonyl group of 4-oxo-l-proline. A method for the cultivation of Streptomyces antibioticus in a closed system with an 18O2-enriched atmosphere was developed. Isolation and purification of the imino acids (hydroxy-l-proline, oxo-l-proline, and l-proline) was accomplished by column and paper chromatography. The hydantoin derivative of the imino acids was prepared and the oxygen-18 in the molecule determined by pyrolysis and mass spectrometry. The source of oxygen in the hydroxyl group of hydroxyproline is atmospheric oxygen rather than water. The carbonyl oxygen atom of oxoproline was found to contain negligible oxygen-18 because of an exchange reaction. Trans-4-F-proline-3H is incorporated into the actinomycins and is hydroxylated by displacement of F to yield trans-4-hydroxyproline. Cis-4-F-proline-3H also is incorporated into the actinomycins; hydroxylation at the trans-4-position appears to take place readily; however, the molecule is unstable and may be converted to oxoproline nonenzymically. © 1969.