title: Detection of menaquinone-6 and a novel methyl-substituted menaquinone-6 in Campylobacter jejuni and Campylobacter fetus subsp. fetus.
abstract: Menaquinone-6 (2-methyl-3-farnesyl-farnesyl-1,4-naphthoquinone) and a methyl-substituted menaquinone-6 (2,[5 or 8]-dimethyl-3-farnesyl-farnesyl-1,4-naphthoquinone) were the major isoprenoid quinones found in membrane preparations of Campylobacter jejuni and Campylobacter fetus subsp. fetus. By reverse-phase high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) the faster-eluting menaquinone-6 co-chromatographed with a menaquinone-6 standard. The identity of menaquinone-6 was confirmed by UV spectrophotometry, mass spectrometry and nuclear magnetic resonance (NMR) analysis. The slower-eluting methyl-substituted menaquinone-6 co-chromatographed with a menaquinone-7 standard by reverse-phase TLC but eluted between menaquinone-6 and menaquinone-7 standards by HPLC. The UV spectrum of the methyl-substituted menaquinone-6 did not correlate with either authentic menaquinone or demethylmenaquinone. Mass spectra showed an increase of 14 mass units when compared to menaquinone-6, and indicated that a methyl substituent was on the naphthoquinone nucleus. NMR spectra confirmed the presence of a methyl substituent at a peri position (carbon-5 or -8) on the benzenoid ring.
mesh_terms: D002168:Campylobacter fetus / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D013056:Spectrophotometry, Ultraviolet; D014812:Vitamin K / Q000031:analogs & derivatives / Q000032:analysis*
chemical_list: D014812:Vitamin K