In:
Canadian Journal of Microbiology, Canadian Science Publishing, Vol. 15, No. 7 ( 1969-07-01), p. 797-807
Abstract:
A comparative study was undertaken to examine the succinate and terminal oxidase activities of the electron-transport systems of Azotobacter vinelandii and mammalian mitochondria. For succinate oxidation, both systems exhibited similar relative specificities for the electron acceptors phenazine methosulfate, O 2 , methylene blue, K 3 Fe(CN) 6 , nitrotetrazolium blue, 2,6-dichlorophenolindophenol (DCIP), and cytochrome c. They differed in that DCIP and cytochrome c were less active in the Azotobacter electron-transport system (R 3 fraction) than in the bovine mitochondrial system. Comparative studies with known inhibitors of mammalian mitochondrial electron-transport demonstrated that the succinoxidase activity of the Azotobacter R 3 fraction was, at least, 2000 times less sensitive to antimycin A, 700 times less sensitive to thenoyl-trifluoroacetone, and 30 times less sensitive to 2-n-heptyl-4-hydroxy-quinoline-N-oxide. Both systems were equally sensitive to KCN, p-chloromercuribenzoic acid, and chlorpromazine.The ability of the two systems to use tetramethyl-p-phenylenediamine (TMPD) and its derivatives as electron donors, for terminal oxidation, was also similar. Studies on steady state reduction revealed that in the Azotobacter R 3 fraction, the cytochromes (a 2 , a 1 , b 1 , c 4 + c 5 ) and flavoprotein components were reduced substantially by succinate as well as by TMPD in the presence of ascorbate. Ultrastructure analyses of the Azotobacter R 3 electron-transport fraction revealed the vesicular membranous components identified as oxidosomes according to the terminology used by DeLey and contained spherical headpiece units of 80 Å in diameter which appeared to be morphologically identical with the tripartite units or the elementary particles described by Green and associates, viz., Kopaczyk et al., and by Fernandez-Moran et al.
Type of Medium:
Online Resource
ISSN:
0008-4166
,
1480-3275
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
1969
detail.hit.zdb_id:
280534-0
detail.hit.zdb_id:
1481972-7
SSG:
12
Permalink
