A new menaquinone homologue was isolated from a nocardioform bacterium, Actinomadura madurae. The isolated compound had ultraviolet and infrared absorption spectra very similar to those of menaquinone. The mass spectrum of the compound showed the molecular ion peak at m/z 790 with the coexistence of two intense fragment ion peaks at m/z 225 and 187. However, two weak fragment ion peaks were not found at m/z 721(M-69) and 653 (M-69-

In a previous paper,!• we stated that the molecular species of menaquinone are very useful for classifying the coryneform and nocardioform bacteria. However, it was re-* The nomenclature and terminology of this quinone follow IUPAC-IUB recommendations 51

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