title: Haemoprotein terminal oxidases in the nematodes Nippostrongylus brasiliensis and Ascaridia galli.
abstract: 1. Mitochondria isolated from the gut-dwelling nematodes Nippostrongylus brasiliensis and Ascaridia galli (muscle and gut + reproductive tissue) were examined for cytochromes, and it was observed that N. brasiliensis and A. galli muscle tissue mitochondria contained a-, b- and c-type cytochromes, but their stoichiometries were quite different (1:2:1.9 and 1:11.4:13.6 respectively); A. galli gut + reproductive-tissue mitochondria, however, only contained b and c cytochromes, in a ratio of 1:0.8. 2. CO difference spectra showed the presence of CO-reacting b-type cytochrome(s) in all three types of mitochondria; the fast-reacting species comprised 30, 44 and 39% of the total in N. brasiliensis, A. galli muscle and A. galli gut + reproductive-tissue mitochondria respectively. 3. Cytochrome aa3 was observed in N. brasiliensis mitochondria and in those from A. galli muscle, but was below the level of detectability (less than 0.005 nmol/mg of protein) for A. galli gut + reproductive-tissue mitochondria. 4. Photochemical action spectra for the reversal of CO inhibition of the endogenous respiration of whole worms (at 24 microM- and 40 microM-O2 respectively for N. brasiliensis and A. galli) gave maxima at 598 and 542-543 nm, corresponding to the alpha- and beta-absorption maxima of cytochrome aa3, and at 567 nm (b-type cytochrome) for both worms. These results suggest that cytochrome aa3 is the major functional oxidase in N. brasiliensis, whereas the CO-reacting b-type cytochrome dominates in A. galli.
authors.affiliation: Department of Microbiology, University College, Wales, U.K.
authors.forename: T A
authors.initials: TA
authors.lastname: Paget
authors.forename: M
authors.initials: M
authors.lastname: Fry
authors.forename: D
authors.initials: D
authors.lastname: Lloyd
mesh_terms: D000818:Animals; D001197:Ascaridia / Q000201:enzymology*; D002248:Carbon Monoxide / Q000378:metabolism; D003580:Cytochromes / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology; D009559:Nippostrongylus / Q000201:enzymology*; D010101:Oxygen Consumption; D010777:Photochemistry; D013053:Spectrophotometry
chemical_list: D003580:Cytochromes; D002248:Carbon Monoxide