KARABEMYCIN, A NEW ANTIMETABOLITE OF GLUTAMINE PRODUCED BY A STRAIN OF STREPTOMYCETE

Abstract

Karabemycin, a new peptide antibiotic, was isolated from the culture filtrate of Streptomyces sp. AM-6424, a soil isolate. The molecular formula of the antibiotic was determined as C₁₅H₂₄N₄O₆ on the basis of elemental analysis, FD-mass spectrum and ¹H and ¹³C NMR. Acid hydrolysate of karabemycin contains one mol each of valine, alanine and an unknown amino acid. The antibiotic is active against Gram-positive and -negative bacteria on a synthetic medium. The inhibitory activity is reversed by L-glutamine and L-glutamic acid.