A soluble CO- and NO-bindingc-type cytochrome inNeisseria meningitidis

Group BNeisseria meningitidis (SDIC) was grown aerobically in Mueller-Hinton medium to stationary phase and then broken either by sonic oscillation or high pressure extrusion from a French pressure cell. The particulate fraction (345,000×g, 3 h) contained cytochromesc, b, o, and evidence of ana-type. The supernatant fraction contained a solublec-type cytochrome (c ₅₄₉). The pyridine hemochrome derivatives of acid-acetone-extracted supernatant fractions were shown to be free of other cytochrome types. The solublec cytochrome increased during the growth cycle of the organism, reaching a maximum after cells entered stationary phase, whereas the cellular level of other cytochromes from the particulate fraction started to decline as cells progressed from log into stationary phase. Osmotic shock, as well as other treatments, failed to selectively release the solublec cytochrome from the cell. When untreated, thec ₅₄₉ in the supernatant fraction remained in a reduced form. While it was not air oxidizable, it was readily oxidizable with K₃Fe(CN)₆. In the reduced form, thec ₅₄₉ bound either CO or NO, but in the oxidized form, only NO was bound. The results obtained from this study indicate that the solublec ₅₄₉ is probably best classified as a cytochromec′.