Tyropeptins A and B, new proteasome inhibitors produced by Kitasatospora sp. MK993-dF2 II. Structure determination and synthesis

Article abstract of DOI:10.7164/antibiotics.54.1004

The structures of tyropeptins A and B, new proteasome inhibitors produced by Kitasatospora sp. MK993-dF2, were determined by analysis of various NMR experiments. The ¹H and ¹³C NMR of tyropeptins were complicated due to the presence of an aldehyde group. Therefore, tyropeptins were converted to their alcohols by sodium borohydride. These alcohol derivatives gave assignable NMR spectra. The stereochemistry of tyropeptins were determined by analysis of acid hydrolysis products from tyropeptins, and further confirmed by the total synthesis. The structures of tyropeptins A and B were found to be isovaleryl-L-tyrosyl-L-valyl-DL-tyrosinal and n-butyryl-L-tyrosyl-L-leucyl-DL-tyrosinal, respectively.