this conclusion was based on the fact that 1 ) both radiolabeled l-proline and trans-4-hydroxy-l-proline are precursors of the bound d-imino acid as noted previously by hook and vining ( ( 1973 ) j. chem . soc . chem . commun . 185-186 ; ( 1973 ) can . j. biochem . 51 , 1630-1637 ) , 2 ) the unlabeled trans isomer specifically inhibited the incorporation of radiolabel from proline into the antibiotic , 3 ) the 14c-hydroxyimino-acid was isolated from the intracellular pool and medium following incubations with l- [ 14c ] proline during antibiotic biosynthesis and when etamycin synthesis was blocked by d-leucine .
C0020931
imino acid
C0033382
proline