128517-07-7 Antibiotic FR 901228 FK 228 FR 901228 FR901228 L-Valine, N-((3S,4E)-3-hydroxy-7-mercapto-1-oxo-4-heptenyl)-D-valyl-D-cysteinyl-(2Z)-2-amino-2-butenoxyl-, (4-1)-lactone, cyclic (1-2)-disulfide L-Valine, N-(3-hydroxy-7-mercapto-1-oxo-4-heptenyl)-D-valyl-D-cysteinyl-(Z)-2,3-didehydro-2-aminobutanoyl-, xi-lactone, cyclic (1-2)-disulfide, (S-(E))- NSC 630176